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On the strength of materials
9~
On the Strength of Materials. the garden, and I Will show you the ~toek that yields me an excel. lent interest." On going to the garden, he showed the bishop a large range of bee-hives. -There is the bank from which I draw
On the Strength of l~lateriats. [From Brunton'sCompendiumof Mechanics,] (Concludedfrom p. 49.) STRENGTH OF THE JOURNALS OF SHAFTS.
t.~temt Strength. ThE Rules in problem 5, of the Iast article, can be here applied, Mr. Robertson.Buehanan, in his Essay on the Strength of Shafts, usea the foltowmgrule, which is simple enough, and easy to b~ remembered; but the above-mentioned rules, are the most correct, and ought to be used on all occasions. Mr. Buchanan's rule is,--', The cube root of the weight in cwts. is nearly equal io the diameter of the j o u r n a l . ' - - " Nearly equal~ ~oeing prudent to make the journal a little more, than less, and to make a due allowance ibr wearing." ¥ hat ,s the diameter of the journal of a water wheel shaff~13 feet tong, the weight of the wheet being 15 tons? By Mr. B.~s rule. ~/15 × 20=6'7 or ~; inches diameter. By Mr. "rredgold . . . . . . ~s =rule. Weight in ~33600 × 1 3 : 7 ; 3~ the middle, t 5-00 ==875 ~ 8 7 5 = 9 ~ inches diameter. Weight equally ( ~ _. s distributed. ~,S500 X 13~456800 J436800 ~ - - - - - 7 . 6 5 inches. 10
7b ties|st Torsion or Twisting. It is obviotwthat flue strength of revolving shafts are directly as the cubes of their diameters and revolutions; and inversety~ as the resistance ~hey have to overcome. : Mri RQbertson Buchanan, in his Essay on the Sti~engfhof Shaf~, gi~es fl~e following data, deduced from several experiments~ viz, that the:fly:wheel shaft of a 50=horse power engine~ a t 50 revolutions per minute, requires to be 7~ inches diameter~ and~ therefore~ the Cubeof' this diameter, which is =4~21.875i serves as a multiplier to atl othershafts in the same proportion;" and taking this as a staudard, he gives:the followlng m~:l~iP!iers, viz.
On the Strength o f Materml, .
95
For the shaft of a steam engine, water wheel, or any shift ~.aO0 connected with a first power~ . . . . . ~ -S For shafts in inside of mills, to drive smaller machinery, ,or ~ ~JO connected with the shafts above, . . . . . ) ~! ~ For the small shafts of a mitt or machinery', -:i 4 0 0 From the foregoing, the following rule {s derived, viz. The number of horses' p~)wer a shaft is equal t% is directly as the cube of the diameter and number of revolutions; and, inversely, as the above multipliers. Note. Shafts here, are understood as the journals of shafts, the bodies of shafts being, generally, made square. TM
Example I. When the tiy wheel shaft of a 45 horse power steam engine, makes 90 revolutions per minute, what is the diameter of the journal? 45 X 400 z~ 9 0 ~ ~ ~00 ~/200~= 5 ~ inches diameter. ~Example 2. The veloeity of a shaft is 80 revolutions per minute, and its diame. ter is S inches: what is its power? Sa ~ U = 5.4 horse power.
Example 5. What will be the diameter of tile shaft in the first example, when used as a shaft of the second multiplier?" ~ . ~ ~= 4.64, or
. . . . . 4 ~ inches diameter. •J 90 The following is a table of the diameters of shafta~ being the first movers, or having 400 for their multipliers. • The dlameter~of the second moverswill be found by dividingthe rmmbers in the table by 1,25~and the diameters of the third moverJ, by div~dln~"the nember~by 1.56,
On lhe Strength o/ Materials.
94
'FABLE. ])IAM~TJER~
O~ Ttl~
ffOIlRlqA~
OF ~I}tST
MO~EI~.
REVOLUTIONS,
tO
151~
35 "i ,0 ~( i 45 I 50 ! i5
;.5
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t.8
.5
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LI 4
t.9
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8.6! 3.5
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I
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L5
t.1
.
3.8
S.7
~.6
7] L6
5.8
L4
tt
4.
5.9
L7
6.
4.6
L 4.2 4.1 L4
P
8
5.9
9
7.9~ 6.3
4.8
[. [.5
tO 7.4 6.6
4.9
1. L7
12 7.~
5.4
5.~
6.9
4.8
L
1
4.6 1
14 8.~ 7.~
5 . 6 5.4
16 8.7
7.6
5.8
18 9.
7.~
6.~ 5.8
20
9.:
8.1
6.4 ,
55.9
5.6
~.4
5.4
~5 10.
8..~
6.8
6 6.3
5.9
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lo 9.~
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6.35 !
7.4 7.1
6.6
6.
7.
6.8
so
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5.6 5.~
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t ....
40 11. [10.;
7.8
45 1~. [10.1
8.1
7 7.4 7 7.( L ~~
50 13. Ill.
~ - 8 " 5 8.
55 l~. I11,
8.8, 8.z
60 INCHES
DIAMETER.
On the Strength of Materials.
95
T A aLF~ CONTINUED.
. l . , ? . wen ~nown tact, tl~at a east-iron rod will sustain m ~ t a r s~ona~pressure, than a malleable iron rod ~if the same dimertsion~. --That ~S,a malleable iron rod will be twisted by~ less weight ~ a a what is required to wrench a cast-iron rod of ti~ same dimens|bas,
96
Oa lhe ,qtrength of zl,lalerials.
Whe~2 the strength of malleable iron is less than that of cast-irorf to resist torsion, it is stronger than cast-iron to resist lateral presture, and that strength is in proportion as 9 is to 14. From the foregoing, it is easy for the millwright to make the shafts t~f the iron best suited to overcome the resistance to which they witl be subject, and the proportion of the diameters of their journatsr according to the iron of which they are made:--fbr example; what will be the diameter of a malleahleiron journal, to sustain a~t equal weight with a cast-iron journal of 7 inches diameter~ 7a= 343. 14 : 343 : : 9 : ~Ok now ~/~0.-----5 ~ 6.04 inches diameter. s'r~EsoTn 0F W~tEELS. The arms of wheels are as levers fixed at one end, and loaded at the other, and, consequently, the greatest strain is upon the end of the arm next the axle; for that reason all arms of wheels should be strongest at that part, and tapering towards the rim. T h e rule for the breadth and thickness of arms, according to their length and number in the wheel, is as fi}llows: (See Tredgold's Essay~ page 114.) Multiply the power or weizht acting at the end of the arm by the cube of its length; the product of which, divided by ~656 times the number of arms multiplied by the deflection, will give the breadth and cube of the depth.
Example. Suppose the force acting at the circumference of a spur wheel to be 1600 lbs. the radius of wheel 6 feet, and number of arms 8, and let the deflection not exceed ~r of an inch. 1600 X 63 ~65,5-~-8--X'ff == t63 = breadth and cube of the depth. 163 Let the breadth be ~.5 inches~ therefore ~ -----65.2, which is equal to the cube of the depth: now the cube root of 65.2 is nearly 4.03 inches; this, consequently, is the depth, or dimension, of each arm in the direction of the fiJrce. Note. When the depth at the rim is intended to be half that of the axes, use 1640 as a divisor, instead of ~656. The teeth are as beams, or cantilevers, fixed at one end and loaded at the other, the rule applying direct to them, (See Tredgold's Essay, .~1ft. I~1,) where the length of the beam is the length of the teeth, and the depth the thickness of the teeth. For the better explanation of the rule, the following example is given.
Example. Thegreatest power acting at the pitch line of the wheel, is 6000 lbs° and the thickness of the teeth tk inch, the length of the teeth being 0.9.,5 feet; it is required to determine the breadth of the teeth. 6000 x o.~5. 15oo .=-,~ ~ ------- ~ 5.~ inches the breadth required.
~lfg x1.5~
477
In orderthat the teeth may be capable of offering a sufficient re-
On the ~D'englh of Materials.
97
sistance after being worn by friction, the breadth thins found shotdd be doubled; therefore, in the above exampl% the breadth sh0uld:be 6.4, or say, 6~ inches. Mr. Carmichael* gives the following data, gleaffed from exp~'iments, which is, therefore, valuable, and of n~uch use to /he lJi~actical mechanic. Rule. M~ltip!y the breadth of the teeth by the square of the thickness, and divide the product by the length'; the quotient will be the proportional strength in horses' power, with a velocity of ~.~7 t~et per second.
Example. W h a t is the power of a wheel, the teeth of which are 6 inches broad, 1.5 inch thick, and 1.8 inch long, and revolving at the velocity of 3 feet per second? 1.5 ~ X 6 15.5 1.8 =--i-.-~.8= 7 . 5 strength at ~.~7 t~et per second. 7.5X3 then ~.~7 : 7.5 : : 3 = - - = 9.91 horse power. ~. ~7 Rule. The pitch is found by multiplying the thickness by ~.1, and the length is found by multiplying the thickness by 1.~.
£~amph.
•
T h e thickness being ~ inches; what is the pitch anti length~ x 2.1 = 4.~ Pitch. X 1.~ X ~.4 Length. Note. The breadth of the teeth, as commonly executed by the best masters, seems to be from about twice to thrice the pi'tch. TABLF_. ~itch in i ~ehes.;
:9
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t
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Breadth[Length Power H.P. t H.~. I ~ , F , I n I in in ~t2,27feet Lt3 feet J t 6 feet ]Lt11 feet] :hes. Inches. Inches. per See. bet See. [ )er See. [
~.99 .78 ~.57
[
ick.
"9 .8
';'8.' ' ",' ~.40
7. 6 7,~ 6.8 6.4" 6. [
~.~8 ~.16 2.04 1.92 1.80
5.6 11.68 5.~ 11.56 4.8 4.4
t 1.441 c, ! / 1.o~i
4.:
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13.53 15.03 10.80 9, 6ff 8.53
7.50 6.55 5.63
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17.61 ]
1 £ 9 0 i 31.8o t 58.~o 14.2Z ~8:54 ]52-;$9 19. 7~ 25,54 I 46,68 H.~7 ~22:54 I 41;$~
9.91
8.65 %44 6. 34
17.26 ]81,64
14.88 i ~?.28 12.68 i ~.q,~4
5.3~ 1Q,6:~ :I:i9.54 4.40
8.81
5,57
7.14 13.09
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.84
e,15 ,6 1.~0 1.59 ~:,t ! .79 ~.1:8 5.SS'I 1.10 ~.os j 1,5 I ,~o .85 * See Robertsoa Buchanan on the Teeth of Wheels.
¥oL. I I [ . - - N o . e.--FE~avA~v, 1899.
!3
On lAe St,rength o f 3IateriaLe.
9S
VELOCITY OF W H E E L S .
Wheels are for conveying motion to the different parts of a m a chine, at tile same, or at a greater or less velocity, as m a y b e r e q u i r e d . ~ W h e n two wheels are iil motion, their teeth act o n o n e another alternately, and, consequently, if one of these w h e e l s ' h a s 40 teeth, and the other 20 teeth, the one with twenty will t u r n t w i c e upon its axis9 for one revolution of the wheel with 40 t e e t h . ~ F r o r n this the rule is taken, which i s , h a s the velocity required is t o t ' t l e number of teeth in the driver.so is the velocity of the d r i v e r t o t h e number of teeth in the driven. Note. To find the proportion that the velocities of the w h e e l s i n a train should bear to one another, subtract the less v e l o c i t y f r o m the greater, and divide the remainder by the number of one l e s s t h a n the wheels in the train; the quotient will be the number r i s i n g i n arithmetical progression, from the least to the greatest v e l o c i t y o f the train of wheels.
E~ample 1. W h a t is the number of teeth in each of three wheels to p r o d u c e 17 revolutions per minute, the driver having 107 teeth, a n d ' m a k i n g 3 revolutions per minute? 17 - - 5 -----14 3 - - I = ~2 - - 7, therefore, 5 1017 are the velocities of t h r e e wheels.
~
10 : ]07 : : 3 : S~ _ _ _ ~ - - - - - 3 2
By the rule.
1 7 ' : $ 2 : : l0
ID = 3 ~ × 1 0 = 17
teeth. 19 teeth.
Example 2. W h a t is the number of teeth in each of 7 wheels, to p r o d u c e t revolution per minute, the driver having ~5 teeth, and m a k i n g 5 6 revolutions per minute? 56
-
-
--I
1
,= 55 =-6
= 9, therefore, 56 2t65728 19 10 1, are the p r o -
gressional velocities. 4 6 : ~5 : : 56 : 50 Teeth. 57 : ~0 : : 46 : 57 ~ .... 28 : 57 : : 37 : 4 9 ~ 19 : 49 : : 28 : 7~ 10 : 7 2 : : 1 9 : 137 1 : 157: : 10 : 1 5 7 0 - I t will be observed that the last wheel, in the foregoing e x a m p l e , is of a size too great for application~ to obviate this difficulty, w h i c h frequently arises in this kind-of training, wheels and pinions a r e used, which give a great-command of velocity.~Suppose t h e v e l o cities of last example, and the train only of ~ wheels and e p i n i o n s . -
56-4~ loeities.
~
5,
18, therefot~ 56 19 1,are the progressional v e -
Or,/Ae Strengt& Of Materials. i9 : £5 : : 56 : 74 ~ teeth in the wheel drb and I : 10 ::: 19 : 190 teeth~ in the second. being in the driving pinion. 25 drivers 74~dnve n'
Io , ~ 1 9 o ~ :
.........
The following is a fable of the radii o f ~heels, from ten ~ithr~.: hundred teeth, the pitch being ~ inCheS:: ~ :::::~ : : ::~!: i The radios for any other pitch may be found by the following,analogy:--as two inches is to the radius in the table, sots the new pitgh to the new radius. TABLE.
•
100
F u f m i n a l i n g Powder f n f l a m m a b l e @ Perc~lssiono TABLE CONTINUED.
67,803 ~50 68.121 ~51 68.499 ~5~ 68.757 ~53 69.075 ~54 69.394 255 69.712 ~56 70.031 ~57 70.549 ~58 70.667 ~59 70.985 260 71.304 ,~61 71.6~2 262 71.941 ~63 72.~58 ~64
79.580 79.898 80.o~16 80,534 8O.855 81,171 81.489 81.808 8~A~6 8~.444 8~.763 88.081 8 3.o99 ~8S.717 84.088
287 288 ~289 290 ~91 292 293 294 295 296 297 298 ~299 500
On~ some Tdnds of ~ulm~nating Powder inflammable by Pereundon, and their ~se in t~re.arms. By P. W. SCnMmT, Lieutenant in the P~u~siau service. ~ A ~wa~ea, inflammable by percussiofi, has been used .years PaS~, especially in fowtihg.pieees.. The following for some "' ~'~" : -i .' fbrmulm " From Set~welgger's~m,nal, .Band x~. p. 66~
have been given for the gredient ofwMch is eh 1. 100 parts of chlo phur~ and 10 parts of are produced by forcin~ 2. I00 parts of chlor of suluhur~ and 14/yurts of lycopodium. -: . Th~se are the usual ingredients that have hitherto been mixeC[ with the chlorate of potash for the purpose of makin~ primin :~ d er. The guns~ however, . . wlth . which . . tins . powder . . is useds are g l ~very various in their construction. In some it primes itself by means of'the mechanism of the lock, passing, on bein~ cocked~ into a small conical recess, which communicates with the tS"ueh-hole; in others, it is put in previous to every shot. In the former kind of guns a quantit~ of powder sufficient for a certain number of shots is kept in a recess attached to the lock, called a magazine; and the locks (which were invented in England by Mr. Forsyth) are caited magazine locks. In some guns the stroke of the cock, which is in the shape of a hammer, falls immediately o~1 the fulminating powder strewed in the above recess. In order to protect the powder from wet, small balls of it were covered over with wax, and placed sometimes in the coMcal ~,ecess, and at others-fixed to the cock itself. In both instances the ball was kindled in the recess just mentioned, by .means of the percussion. Besides these, other contrivances have been used for the imrpose of igniting this kind of"powder; yet they have all their defects, ~nd offer so many difficulties in practice as to have prevented their general introduction. Latterly, they have contrived in Germany to fix the poW~ler~i~Ua~ small case of vdry thin copper MI, for the purpose of keepinzit dr: .' and fbr that. purpose a cylinder is screwed into the bod¥'of;h.. ~ ! ms~eaa o t ~ e toueMmle, and rests, for fl~ ~2~.2 =d=~Y:..'~'~ 6~':" • ,. -..~at, t: vt .~.rcater gljDDOrT ~ on the plate of the lock, instead of resting on the ffan The'i'nner space of the cv/~nd~. ;= fi I I ~ , l . ' ~ I ~ ~ : . . . . . . . . ~ *
102
Fulminating tJowder In,flammable by Percussion.
other; it produces neither dirt nor moisture; it is n o t so liable to ex+ plode as the other powder, and if it does explode~ its effects are lesm destr'i~ctive, inasmuch as its power does not e x t e n d so tar. The followin~ is his mode of pret~aration: ~ , , +'I place two'drachms of quicksi'lver in a F l o r e n c e llasK, ann p.our six drachms (measure] of pure nitric acid on tile inercury: thts I place in a stand over a spirit lamp, and make it boil till the quicksilver is taken up by the acidj when nearly cool, I p o u r i t o n anounee (measure) of alcohol in another flask: Sometimes imnaeutate e~e.rveseenee ensues, with the extrication of nitrous a~ther~ an ct otten I have been obliged to place the mixture over the lamp, till a white fume begins to rise, when the ett~rvescence follows. I s u f f e r the process to continue (removing the lamp) till the fumes a s s u m e a reddish hue; when I pour water into the flask-, and the powder is found precipitated to the bottom~ 1 pout" off and add fresh Water, permitting the each time before the water is p+ o u r e .d of;; so as to p owder to subside , free the substance as much as possible from the a c t d , and then I our it on a piece of fitterin~ paper, and olace the p o w d e r i n an airy rP3om to dry.- It should be ~ei~t'in a corl~ed (not s t o p p e r e d ) bottle." For tile filling of the caps, he makes use of a n ivory" rod, which has a scoo at one end for the purpose of receivin~ t h e powder, and at the other is cut flat; with t'his'he puts in as ~ a u c h fulminating mercury as will cover the bottomi he then dips t h e flat end into a strong tincture of" benzoin, and rubs this substance g e n t l y about the case~ by which means the powder is set fast and c o v e r e d as with a varnish. Professor Schweigger, speaking,of these kinds o f experiments in his chemical lectures, noticed the difficulty of k i n d l i n g gunpowder by the mere admixture of such substances, as has b e e n shower in a criminal investigation that took" place at Munich a f e w years ago. 3_ box filled with gunpowder was sent to an individual ; e n closed were fulminating papers, which were to inflame on the b o x being opened. Fortunately, however, the murderous design was f r u s t r a t e d ; for although the papers exploded, they did not kindle t h e powder. The assassin was discovered and punished. M. G e h l e n , w h o had been examined at the trial, was led by the circumstance to m a k e several experiments fbr the purpose of'kindling g u n p o w d e r b y means of Brugnatelli's ihlminating silver, but they all failed. It seems that i6 England, too, difficulties had b e e n found in igserves, "" 7 P " "" y " ggunpo Y means of fulminating me,-cury, by procuring ,a, percussion-gun, he may try the experiment and be frilly satisfied. ~ P,'ofessor S c h w e i ~ e r having, therefore, requested m e to try" some experiments on this subjeet, especm ly w~th fulmmatin~ silver, 1 made them inthe chemical laboratory of our universify,+an~ "the following were the results. " • [. Fulminating silver was prepared in the usual w'av~ five drac ~ms of fuming mtrtc acLd, and tlve of ~t~:~m~were pou~'ed o v e r one drachm ¢t fused mttate of.mlver. Whcnthe~ffervescence a n d solution werc
Fulminating
Powder
l n f l a m m , able,b~I Pe~g~'sion~
103
complete, water ~wasadded. The precipitate of fu|raia~t ~ si!~er was filtered off, and all the remaining acidity washed~f~t ~:]t(~i;~h water. The hqmd which had passed throughAhe.fllter gav~!~':~j~h murlatic acid a-copious precipitate of Chloride bf s~i~ei:~ ~ ~be ~f~l!~]: nating silver, which was of a whitish tint, was now subje¢ t~d)i~to~ti{¢ following experiments: . .~ ~".,; ~:~ ' :.:,:(!~:~]~L I, When.dam p, it ignited, very rarely,, and only~by ' . a: St'i:0ngl~ioW,~ When dry, ~t explodes easdy, and w~th a much shghterblow., •:, ~. When touched with sulphuric acid, it exploded equallystrofig}y~ whether damp or dry. , ~i 8 Damp or dry, it exploded in the fire . . . . 4. The Substance which remained after ° the ignition, )was of~a bluish brilliant hue and a disagreeable metallic t~ste, i couldgather but little, which, dissolved in water, produced a faint>red tint on litn~us paper. 5. I failetl in several attempts to ignite gunpowder with the fulminating silver. I therefore put quautit'es of the size of a small pin's head, into some copper boxes, fzstening it in some with tincture of benzoin, in others with a solution of gum arabic in water; and others I tried to press on the bottom without any other aid. I applied them to guns prepared for the use of igniting-caps, antl thus kindled the gunpowder with incredible swiftness. , ~'he s~ieS of e x~-: periments thus made in the presence of Profbssor Sc'hweigg¢~[!eR~eS no doubt that fulminating silver will easily ignite gunpo~d'e?, if ilt be secured against a rapid dispersion on exp]o~;~g, : ~i, i ~. ! II. The fulminating mercury was prepared ]~the, manner pr~,, scribed byMr. Wright. But I must observe that the experim~nf ~ only succeeded by the application of fumin~ nitric acid. Th~ ful~ minuting mercury, when obtained, was washed till eve~ pa/!fi'~]~:of acidity had disappeared from it. It ,~as then submitted~t0 .~14~f01'~ lowln~ ~xnarlments:
104
Futmi~zaling. Powder' ln/Iamrnable b?l Pe~.c~tssion.
being the property of all metals, he distinguishe.q into silver and mercury fuhainic'aeid,% &c. • The great advantages, however, of the fldminating quicksilver for igniting powder, s~ extolled by Mr, Wright, I did not find confh'me.d, , . ~. I p roeeeded - to tLll c)pper caps, as I had done wi~h tt)e althou-h t uetonatLng silver, which all ignited the charge. I l l . I also submitted to efperiment the fi;st-natued miXture, principally consisting o~" chlorate of potash~ and found I. T h a t it exploded only by a hard blow. Its ett~cts were much !ess than those of the detonati]~g silver, or quicksilver. M r. W r i g h t , indeed, says the contrary of the latter; it seems, therefore~ t h a t I used a better k i n d of fulminating mercu,'v~ but for that Very reason [ must give the chlorate of potash the preTerence for practical use. ~, In the fire it puffed away like gunpowder. , : . , ~, T h e s u b s t a n c e remaining after the explosion is blackish anti dusty, and c o n t a i n s tess of aci'~lfly than that left by the quicksilver. Fhus, and i n d e e d fi-om all my experiments, it is evldent that it oxtdizes ~he iron less than the fulminating mercury. Moisture is al~so left by the latter'; and the charcoal left by the ~aixture of chlorate of potash~ after ki~dling a copper cap filled with it, is v e r y unimporta n t : ~ t h e r e [ b r e this mixture is p'referable as an igniting powder. This is also the reason why the manufacturers no longer use the fulminating quicksilver, f know one who makes and fills, weekly, several t h o u s a n d s of copper caps~ for which he uses the chlorate mixture, the preparation of which is both less expensive and less dangerous than that of the fulminating quicksilver. =T h e r e is another cireutustanee .'~ttending this mixture; i n fi!ling the caps, it .nateUi's detonating" silver ~vagdissolved in lime-water or solutions of the Caustic alkalies, whereby 31,~25per ccnt of oxide of silver was deposited. They produce peculiar sMts, callcd futminafe*,which explode with g'reat violence, Thesd'*salts are dissolved by nitric acid, sulphurlc acid, and aerie tteid; the silver fidminie acid contained" in them, and so difficult to be dissolved, is de~bsited; a~ld by heating a solution of fidmiaate of lime to the boiling polar, and] adding" :t motlerate quantity of nitrle acid, is deposited, 0n eo01inff, at the bottom of the vessel~ in the shape of Ionic white crystals. This aeidmaybe easily dissolved in boitillg" water; from which it crystallizes again in cooling', has a disffustlng" metallic taste, and reddens litmus paper: but. it cannot subsist of itself without eombirmtion with a metal; and ~n the samemanner as.there are prussiales of irol~, copper, silver and gold, so the fidmlnie acid eomblnes with sil-~er, quicksilver, cop[~.er, iro~, zh~c, &e. into proper fftminates~ Whleh..a~h form different combinations with the bases e. g. potash~ soda, barytesi stronttan, li~me; &e. Thus, for instance, sitvcr-fidminate of potas!t com;i~ of 35,03 parts of silver-fuhnhfie aehl and. 14,92 of potash; silver.fidmlnate of sod~, of 88,66 parts ofsit*ree-fi~lmh~ieach! and 1i,34 of alkali. When eot~llng~Berthollet's detonating" silverfi)rms granular shinln~, white crystals. One part 0f-this salt makes as violent a ~eport as three parts of Howard s (Brug'nat~lli's)folmhaatinw silver' -With msgnlesm the- s~lver-ft~tmmtc acid combine a ta two ways~ one combmatlon is?k simple decrep~tating', not detonating, insoluble powdei', Of a rosy tlnti the other foi'ms white capillary crystals, and explodes:very loudly. Ti~'e first eombinat io;l ~ a s used for the ai~aly~of thlmini¢ ~ in the.ctry :flay; ]in: wlileh the fulminating" s~tver wa.s evil,red to~nsiSt 9£3~of:~$k,~t,, 3.~:~ Of hr¢~lrog'en, ll,28 ofazofe, 9,6V3ot'earbon,a6~;41 ofsil~er; :~*::~:~"~," 7. . . . .
Manufacture of S~gar of Lead.
105
will sometimes happen that the quantity put in is douhled~hieh:I find is of no injuri'ohs consequence witli this mixturej butm{~ht endanger the person firing with the fulminating mercury, as t~e~,cap wilt burst too violently." : ": With respect to the power of igniting the charge, the different kinds of powder which I have compared are equally effectual. IV. I-submitted the mixture of chlorate-of l~otash mentioned above to the following experiments. 1. That part only ignited which was struck9 without igniting that lyin~ around it. ~. In the fire it burns away with noise. 3. I placed it in the usual way in copper caps, but could not ignite a charge with them. The cause of this may be explained by the construction of the locks, with reference to the properties of this detonatingpowder. That part of the cap situated just above the opening ot" the cylinder remains, as the blow cannot fall on it unignited, as shown by the experiment No. 1. But the communication of the ignited part with the charge, is prevented by the manner in which t|le cock strikes the cap. In guns in which such powder is used for igniting, it lies as above stated, in small balls in a conical aperture. Hero it is nearly all ignited by the striking of the cock, and must of necessity flow inwards, every other wayofescape being shu~ up. In conclusion , ~ I have to add that the method of filling the caps recommended by Mr. ~Vri~ht is not only laborious, but even dangerous. ~How are manufacturers to eml~loy that method when they have to fill several thousands a week? I have made various t~ials, and the followin~ process seems to me to be the best. Pour some adffesive solution or tincture over the powder, and mix it into a stiff"kind of liquid. Take with a brush or a stick a large drop of it, and appl,¢ it against the bottom of the cap. T his . method . . is .both quick and free from danger; whilst on filling with the dry detonatinff powder, the least careless totteh may produce an exl~losion. In order to prevent the corrosion of the cylinder, and its beeom. ing useless bv the formation of sulphuret of iron (an evil very ecruon with iron touch-holes, and caused more by the action of the gun-.powder than by that of the igniting substance,).the inside, ofthe cyhnder should be lined with a metal which will neither oxidaten0r easily combine with the ingredients of the powdei-.~[Ph//os. ~ o
Manufactureof Sugar of Lead. Tins salt is art object of considerable interest on account of the great use made of it in caliCo-priuting~ as well as in some other arts; In the calico-nrintin~, business, it is in reality one of the ,most U~,/ll preparations;~r according to the French term. which m a n y ~ the English writers wish t o ~aturalize among us, mordant, or biter-in. VoL l l I . ~ N o . ~.~F~gnRVArtv, 18~9. 14
On the Strength of Materials. the garden, and I Will show you the ~toek that yields me an excel. lent interest." On going to the garden, he showed the bishop a large range of bee-hives. -There is the bank from which I draw
On the Strength of l~lateriats. [From Brunton'sCompendiumof Mechanics,] (Concludedfrom p. 49.) STRENGTH OF THE JOURNALS OF SHAFTS.
t.~temt Strength. ThE Rules in problem 5, of the Iast article, can be here applied, Mr. Robertson.Buehanan, in his Essay on the Strength of Shafts, usea the foltowmgrule, which is simple enough, and easy to b~ remembered; but the above-mentioned rules, are the most correct, and ought to be used on all occasions. Mr. Buchanan's rule is,--', The cube root of the weight in cwts. is nearly equal io the diameter of the j o u r n a l . ' - - " Nearly equal~ ~oeing prudent to make the journal a little more, than less, and to make a due allowance ibr wearing." ¥ hat ,s the diameter of the journal of a water wheel shaff~13 feet tong, the weight of the wheet being 15 tons? By Mr. B.~s rule. ~/15 × 20=6'7 or ~; inches diameter. By Mr. "rredgold . . . . . . ~s =rule. Weight in ~33600 × 1 3 : 7 ; 3~ the middle, t 5-00 ==875 ~ 8 7 5 = 9 ~ inches diameter. Weight equally ( ~ _. s distributed. ~,S500 X 13~456800 J436800 ~ - - - - - 7 . 6 5 inches. 10
7b ties|st Torsion or Twisting. It is obviotwthat flue strength of revolving shafts are directly as the cubes of their diameters and revolutions; and inversety~ as the resistance ~hey have to overcome. : Mri RQbertson Buchanan, in his Essay on the Sti~engfhof Shaf~, gi~es fl~e following data, deduced from several experiments~ viz, that the:fly:wheel shaft of a 50=horse power engine~ a t 50 revolutions per minute, requires to be 7~ inches diameter~ and~ therefore~ the Cubeof' this diameter, which is =4~21.875i serves as a multiplier to atl othershafts in the same proportion;" and taking this as a staudard, he gives:the followlng m~:l~iP!iers, viz.
On the Strength o f Materml, .
95
For the shaft of a steam engine, water wheel, or any shift ~.aO0 connected with a first power~ . . . . . ~ -S For shafts in inside of mills, to drive smaller machinery, ,or ~ ~JO connected with the shafts above, . . . . . ) ~! ~ For the small shafts of a mitt or machinery', -:i 4 0 0 From the foregoing, the following rule {s derived, viz. The number of horses' p~)wer a shaft is equal t% is directly as the cube of the diameter and number of revolutions; and, inversely, as the above multipliers. Note. Shafts here, are understood as the journals of shafts, the bodies of shafts being, generally, made square. TM
Example I. When the tiy wheel shaft of a 45 horse power steam engine, makes 90 revolutions per minute, what is the diameter of the journal? 45 X 400 z~ 9 0 ~ ~ ~00 ~/200~= 5 ~ inches diameter. ~Example 2. The veloeity of a shaft is 80 revolutions per minute, and its diame. ter is S inches: what is its power? Sa ~ U = 5.4 horse power.
Example 5. What will be the diameter of tile shaft in the first example, when used as a shaft of the second multiplier?" ~ . ~ ~= 4.64, or
. . . . . 4 ~ inches diameter. •J 90 The following is a table of the diameters of shafta~ being the first movers, or having 400 for their multipliers. • The dlameter~of the second moverswill be found by dividingthe rmmbers in the table by 1,25~and the diameters of the third moverJ, by div~dln~"the nember~by 1.56,
On lhe Strength o/ Materials.
94
'FABLE. ])IAM~TJER~
O~ Ttl~
ffOIlRlqA~
OF ~I}tST
MO~EI~.
REVOLUTIONS,
tO
151~
35 "i ,0 ~( i 45 I 50 ! i5
;.5
[.81
t.8
.5
3.S i S . e
,,I
LI 4
t.9
.7 .i
8.6! 3.5
.~
5 I ;.9
I
6 [ i.5
L5
t.1
.
3.8
S.7
~.6
7] L6
5.8
L4
tt
4.
5.9
L7
6.
4.6
L 4.2 4.1 L4
P
8
5.9
9
7.9~ 6.3
4.8
[. [.5
tO 7.4 6.6
4.9
1. L7
12 7.~
5.4
5.~
6.9
4.8
L
1
4.6 1
14 8.~ 7.~
5 . 6 5.4
16 8.7
7.6
5.8
18 9.
7.~
6.~ 5.8
20
9.:
8.1
6.4 ,
55.9
5.6
~.4
5.4
~5 10.
8..~
6.8
6 6.3
5.9
5.
lo 9.~
7.,
6.9
6.5
6.35 !
7.4 7.1
6.6
6.
7.
6.8
so
' '
5.6 5.~
6"I I
t ....
40 11. [10.;
7.8
45 1~. [10.1
8.1
7 7.4 7 7.( L ~~
50 13. Ill.
~ - 8 " 5 8.
55 l~. I11,
8.8, 8.z
60 INCHES
DIAMETER.
On the Strength of Materials.
95
T A aLF~ CONTINUED.
. l . , ? . wen ~nown tact, tl~at a east-iron rod will sustain m ~ t a r s~ona~pressure, than a malleable iron rod ~if the same dimertsion~. --That ~S,a malleable iron rod will be twisted by~ less weight ~ a a what is required to wrench a cast-iron rod of ti~ same dimens|bas,
96
Oa lhe ,qtrength of zl,lalerials.
Whe~2 the strength of malleable iron is less than that of cast-irorf to resist torsion, it is stronger than cast-iron to resist lateral presture, and that strength is in proportion as 9 is to 14. From the foregoing, it is easy for the millwright to make the shafts t~f the iron best suited to overcome the resistance to which they witl be subject, and the proportion of the diameters of their journatsr according to the iron of which they are made:--fbr example; what will be the diameter of a malleahleiron journal, to sustain a~t equal weight with a cast-iron journal of 7 inches diameter~ 7a= 343. 14 : 343 : : 9 : ~Ok now ~/~0.-----5 ~ 6.04 inches diameter. s'r~EsoTn 0F W~tEELS. The arms of wheels are as levers fixed at one end, and loaded at the other, and, consequently, the greatest strain is upon the end of the arm next the axle; for that reason all arms of wheels should be strongest at that part, and tapering towards the rim. T h e rule for the breadth and thickness of arms, according to their length and number in the wheel, is as fi}llows: (See Tredgold's Essay~ page 114.) Multiply the power or weizht acting at the end of the arm by the cube of its length; the product of which, divided by ~656 times the number of arms multiplied by the deflection, will give the breadth and cube of the depth.
Example. Suppose the force acting at the circumference of a spur wheel to be 1600 lbs. the radius of wheel 6 feet, and number of arms 8, and let the deflection not exceed ~r of an inch. 1600 X 63 ~65,5-~-8--X'ff == t63 = breadth and cube of the depth. 163 Let the breadth be ~.5 inches~ therefore ~ -----65.2, which is equal to the cube of the depth: now the cube root of 65.2 is nearly 4.03 inches; this, consequently, is the depth, or dimension, of each arm in the direction of the fiJrce. Note. When the depth at the rim is intended to be half that of the axes, use 1640 as a divisor, instead of ~656. The teeth are as beams, or cantilevers, fixed at one end and loaded at the other, the rule applying direct to them, (See Tredgold's Essay, .~1ft. I~1,) where the length of the beam is the length of the teeth, and the depth the thickness of the teeth. For the better explanation of the rule, the following example is given.
Example. Thegreatest power acting at the pitch line of the wheel, is 6000 lbs° and the thickness of the teeth tk inch, the length of the teeth being 0.9.,5 feet; it is required to determine the breadth of the teeth. 6000 x o.~5. 15oo .=-,~ ~ ------- ~ 5.~ inches the breadth required.
~lfg x1.5~
477
In orderthat the teeth may be capable of offering a sufficient re-
On the ~D'englh of Materials.
97
sistance after being worn by friction, the breadth thins found shotdd be doubled; therefore, in the above exampl% the breadth sh0uld:be 6.4, or say, 6~ inches. Mr. Carmichael* gives the following data, gleaffed from exp~'iments, which is, therefore, valuable, and of n~uch use to /he lJi~actical mechanic. Rule. M~ltip!y the breadth of the teeth by the square of the thickness, and divide the product by the length'; the quotient will be the proportional strength in horses' power, with a velocity of ~.~7 t~et per second.
Example. W h a t is the power of a wheel, the teeth of which are 6 inches broad, 1.5 inch thick, and 1.8 inch long, and revolving at the velocity of 3 feet per second? 1.5 ~ X 6 15.5 1.8 =--i-.-~.8= 7 . 5 strength at ~.~7 t~et per second. 7.5X3 then ~.~7 : 7.5 : : 3 = - - = 9.91 horse power. ~. ~7 Rule. The pitch is found by multiplying the thickness by ~.1, and the length is found by multiplying the thickness by 1.~.
£~amph.
•
T h e thickness being ~ inches; what is the pitch anti length~ x 2.1 = 4.~ Pitch. X 1.~ X ~.4 Length. Note. The breadth of the teeth, as commonly executed by the best masters, seems to be from about twice to thrice the pi'tch. TABLF_. ~itch in i ~ehes.;
:9
~.36j
.e, .7 .6 .5 .4 .S
L94 I
t
L5~ ] .1
'.1ol
.891 t.68 !
U47
, HOI'Ses
I I
~
Breadth[Length Power H.P. t H.~. I ~ , F , I n I in in ~t2,27feet Lt3 feet J t 6 feet ]Lt11 feet] :hes. Inches. Inches. per See. bet See. [ )er See. [
~.99 .78 ~.57
[
ick.
"9 .8
';'8.' ' ",' ~.40
7. 6 7,~ 6.8 6.4" 6. [
~.~8 ~.16 2.04 1.92 1.80
5.6 11.68 5.~ 11.56 4.8 4.4
t 1.441 c, ! / 1.o~i
4.:
I !.~o
,.08
o.2
] ;96
~.8
/
13.53 15.03 10.80 9, 6ff 8.53
7.50 6.55 5.63
4i8o 4.bS 3,33 ~.70
17.61 ]
1 £ 9 0 i 31.8o t 58.~o 14.2Z ~8:54 ]52-;$9 19. 7~ 25,54 I 46,68 H.~7 ~22:54 I 41;$~
9.91
8.65 %44 6. 34
17.26 ]81,64
14.88 i ~?.28 12.68 i ~.q,~4
5.3~ 1Q,6:~ :I:i9.54 4.40
8.81
5,57
7.14 13.09
16.15 I
5,6~ iO.S3
.so 7,88:t
.84
e,15 ,6 1.~0 1.59 ~:,t ! .79 ~.1:8 5.SS'I 1.10 ~.os j 1,5 I ,~o .85 * See Robertsoa Buchanan on the Teeth of Wheels.
¥oL. I I [ . - - N o . e.--FE~avA~v, 1899.
!3
On lAe St,rength o f 3IateriaLe.
9S
VELOCITY OF W H E E L S .
Wheels are for conveying motion to the different parts of a m a chine, at tile same, or at a greater or less velocity, as m a y b e r e q u i r e d . ~ W h e n two wheels are iil motion, their teeth act o n o n e another alternately, and, consequently, if one of these w h e e l s ' h a s 40 teeth, and the other 20 teeth, the one with twenty will t u r n t w i c e upon its axis9 for one revolution of the wheel with 40 t e e t h . ~ F r o r n this the rule is taken, which i s , h a s the velocity required is t o t ' t l e number of teeth in the driver.so is the velocity of the d r i v e r t o t h e number of teeth in the driven. Note. To find the proportion that the velocities of the w h e e l s i n a train should bear to one another, subtract the less v e l o c i t y f r o m the greater, and divide the remainder by the number of one l e s s t h a n the wheels in the train; the quotient will be the number r i s i n g i n arithmetical progression, from the least to the greatest v e l o c i t y o f the train of wheels.
E~ample 1. W h a t is the number of teeth in each of three wheels to p r o d u c e 17 revolutions per minute, the driver having 107 teeth, a n d ' m a k i n g 3 revolutions per minute? 17 - - 5 -----14 3 - - I = ~2 - - 7, therefore, 5 1017 are the velocities of t h r e e wheels.
~
10 : ]07 : : 3 : S~ _ _ _ ~ - - - - - 3 2
By the rule.
1 7 ' : $ 2 : : l0
ID = 3 ~ × 1 0 = 17
teeth. 19 teeth.
Example 2. W h a t is the number of teeth in each of 7 wheels, to p r o d u c e t revolution per minute, the driver having ~5 teeth, and m a k i n g 5 6 revolutions per minute? 56
-
-
--I
1
,= 55 =-6
= 9, therefore, 56 2t65728 19 10 1, are the p r o -
gressional velocities. 4 6 : ~5 : : 56 : 50 Teeth. 57 : ~0 : : 46 : 57 ~ .... 28 : 57 : : 37 : 4 9 ~ 19 : 49 : : 28 : 7~ 10 : 7 2 : : 1 9 : 137 1 : 157: : 10 : 1 5 7 0 - I t will be observed that the last wheel, in the foregoing e x a m p l e , is of a size too great for application~ to obviate this difficulty, w h i c h frequently arises in this kind-of training, wheels and pinions a r e used, which give a great-command of velocity.~Suppose t h e v e l o cities of last example, and the train only of ~ wheels and e p i n i o n s . -
56-4~ loeities.
~
5,
18, therefot~ 56 19 1,are the progressional v e -
Or,/Ae Strengt& Of Materials. i9 : £5 : : 56 : 74 ~ teeth in the wheel drb and I : 10 ::: 19 : 190 teeth~ in the second. being in the driving pinion. 25 drivers 74~dnve n'
Io , ~ 1 9 o ~ :
.........
The following is a fable of the radii o f ~heels, from ten ~ithr~.: hundred teeth, the pitch being ~ inCheS:: ~ :::::~ : : ::~!: i The radios for any other pitch may be found by the following,analogy:--as two inches is to the radius in the table, sots the new pitgh to the new radius. TABLE.
•
100
F u f m i n a l i n g Powder f n f l a m m a b l e @ Perc~lssiono TABLE CONTINUED.
67,803 ~50 68.121 ~51 68.499 ~5~ 68.757 ~53 69.075 ~54 69.394 255 69.712 ~56 70.031 ~57 70.549 ~58 70.667 ~59 70.985 260 71.304 ,~61 71.6~2 262 71.941 ~63 72.~58 ~64
79.580 79.898 80.o~16 80,534 8O.855 81,171 81.489 81.808 8~A~6 8~.444 8~.763 88.081 8 3.o99 ~8S.717 84.088
287 288 ~289 290 ~91 292 293 294 295 296 297 298 ~299 500
On~ some Tdnds of ~ulm~nating Powder inflammable by Pereundon, and their ~se in t~re.arms. By P. W. SCnMmT, Lieutenant in the P~u~siau service. ~ A ~wa~ea, inflammable by percussiofi, has been used .years PaS~, especially in fowtihg.pieees.. The following for some "' ~'~" : -i .' fbrmulm " From Set~welgger's~m,nal, .Band x~. p. 66~
have been given for the gredient ofwMch is eh 1. 100 parts of chlo phur~ and 10 parts of are produced by forcin~ 2. I00 parts of chlor of suluhur~ and 14/yurts of lycopodium. -: . Th~se are the usual ingredients that have hitherto been mixeC[ with the chlorate of potash for the purpose of makin~ primin :~ d er. The guns~ however, . . wlth . which . . tins . powder . . is useds are g l ~very various in their construction. In some it primes itself by means of'the mechanism of the lock, passing, on bein~ cocked~ into a small conical recess, which communicates with the tS"ueh-hole; in others, it is put in previous to every shot. In the former kind of guns a quantit~ of powder sufficient for a certain number of shots is kept in a recess attached to the lock, called a magazine; and the locks (which were invented in England by Mr. Forsyth) are caited magazine locks. In some guns the stroke of the cock, which is in the shape of a hammer, falls immediately o~1 the fulminating powder strewed in the above recess. In order to protect the powder from wet, small balls of it were covered over with wax, and placed sometimes in the coMcal ~,ecess, and at others-fixed to the cock itself. In both instances the ball was kindled in the recess just mentioned, by .means of the percussion. Besides these, other contrivances have been used for the imrpose of igniting this kind of"powder; yet they have all their defects, ~nd offer so many difficulties in practice as to have prevented their general introduction. Latterly, they have contrived in Germany to fix the poW~ler~i~Ua~ small case of vdry thin copper MI, for the purpose of keepinzit dr: .' and fbr that. purpose a cylinder is screwed into the bod¥'of;h.. ~ ! ms~eaa o t ~ e toueMmle, and rests, for fl~ ~2~.2 =d=~Y:..'~'~ 6~':" • ,. -..~at, t: vt .~.rcater gljDDOrT ~ on the plate of the lock, instead of resting on the ffan The'i'nner space of the cv/~nd~. ;= fi I I ~ , l . ' ~ I ~ ~ : . . . . . . . . ~ *
102
Fulminating tJowder In,flammable by Percussion.
other; it produces neither dirt nor moisture; it is n o t so liable to ex+ plode as the other powder, and if it does explode~ its effects are lesm destr'i~ctive, inasmuch as its power does not e x t e n d so tar. The followin~ is his mode of pret~aration: ~ , , +'I place two'drachms of quicksi'lver in a F l o r e n c e llasK, ann p.our six drachms (measure] of pure nitric acid on tile inercury: thts I place in a stand over a spirit lamp, and make it boil till the quicksilver is taken up by the acidj when nearly cool, I p o u r i t o n anounee (measure) of alcohol in another flask: Sometimes imnaeutate e~e.rveseenee ensues, with the extrication of nitrous a~ther~ an ct otten I have been obliged to place the mixture over the lamp, till a white fume begins to rise, when the ett~rvescence follows. I s u f f e r the process to continue (removing the lamp) till the fumes a s s u m e a reddish hue; when I pour water into the flask-, and the powder is found precipitated to the bottom~ 1 pout" off and add fresh Water, permitting the each time before the water is p+ o u r e .d of;; so as to p owder to subside , free the substance as much as possible from the a c t d , and then I our it on a piece of fitterin~ paper, and olace the p o w d e r i n an airy rP3om to dry.- It should be ~ei~t'in a corl~ed (not s t o p p e r e d ) bottle." For tile filling of the caps, he makes use of a n ivory" rod, which has a scoo at one end for the purpose of receivin~ t h e powder, and at the other is cut flat; with t'his'he puts in as ~ a u c h fulminating mercury as will cover the bottomi he then dips t h e flat end into a strong tincture of" benzoin, and rubs this substance g e n t l y about the case~ by which means the powder is set fast and c o v e r e d as with a varnish. Professor Schweigger, speaking,of these kinds o f experiments in his chemical lectures, noticed the difficulty of k i n d l i n g gunpowder by the mere admixture of such substances, as has b e e n shower in a criminal investigation that took" place at Munich a f e w years ago. 3_ box filled with gunpowder was sent to an individual ; e n closed were fulminating papers, which were to inflame on the b o x being opened. Fortunately, however, the murderous design was f r u s t r a t e d ; for although the papers exploded, they did not kindle t h e powder. The assassin was discovered and punished. M. G e h l e n , w h o had been examined at the trial, was led by the circumstance to m a k e several experiments fbr the purpose of'kindling g u n p o w d e r b y means of Brugnatelli's ihlminating silver, but they all failed. It seems that i6 England, too, difficulties had b e e n found in igserves, "" 7 P " "" y " ggunpo Y means of fulminating me,-cury, by procuring ,a, percussion-gun, he may try the experiment and be frilly satisfied. ~ P,'ofessor S c h w e i ~ e r having, therefore, requested m e to try" some experiments on this subjeet, especm ly w~th fulmmatin~ silver, 1 made them inthe chemical laboratory of our universify,+an~ "the following were the results. " • [. Fulminating silver was prepared in the usual w'av~ five drac ~ms of fuming mtrtc acLd, and tlve of ~t~:~m~were pou~'ed o v e r one drachm ¢t fused mttate of.mlver. Whcnthe~ffervescence a n d solution werc
Fulminating
Powder
l n f l a m m , able,b~I Pe~g~'sion~
103
complete, water ~wasadded. The precipitate of fu|raia~t ~ si!~er was filtered off, and all the remaining acidity washed~f~t ~:]t(~i;~h water. The hqmd which had passed throughAhe.fllter gav~!~':~j~h murlatic acid a-copious precipitate of Chloride bf s~i~ei:~ ~ ~be ~f~l!~]: nating silver, which was of a whitish tint, was now subje¢ t~d)i~to~ti{¢ following experiments: . .~ ~".,; ~:~ ' :.:,:(!~:~]~L I, When.dam p, it ignited, very rarely,, and only~by ' . a: St'i:0ngl~ioW,~ When dry, ~t explodes easdy, and w~th a much shghterblow., •:, ~. When touched with sulphuric acid, it exploded equallystrofig}y~ whether damp or dry. , ~i 8 Damp or dry, it exploded in the fire . . . . 4. The Substance which remained after ° the ignition, )was of~a bluish brilliant hue and a disagreeable metallic t~ste, i couldgather but little, which, dissolved in water, produced a faint>red tint on litn~us paper. 5. I failetl in several attempts to ignite gunpowder with the fulminating silver. I therefore put quautit'es of the size of a small pin's head, into some copper boxes, fzstening it in some with tincture of benzoin, in others with a solution of gum arabic in water; and others I tried to press on the bottom without any other aid. I applied them to guns prepared for the use of igniting-caps, antl thus kindled the gunpowder with incredible swiftness. , ~'he s~ieS of e x~-: periments thus made in the presence of Profbssor Sc'hweigg¢~[!eR~eS no doubt that fulminating silver will easily ignite gunpo~d'e?, if ilt be secured against a rapid dispersion on exp]o~;~g, : ~i, i ~. ! II. The fulminating mercury was prepared ]~the, manner pr~,, scribed byMr. Wright. But I must observe that the experim~nf ~ only succeeded by the application of fumin~ nitric acid. Th~ ful~ minuting mercury, when obtained, was washed till eve~ pa/!fi'~]~:of acidity had disappeared from it. It ,~as then submitted~t0 .~14~f01'~ lowln~ ~xnarlments:
104
Futmi~zaling. Powder' ln/Iamrnable b?l Pe~.c~tssion.
being the property of all metals, he distinguishe.q into silver and mercury fuhainic'aeid,% &c. • The great advantages, however, of the fldminating quicksilver for igniting powder, s~ extolled by Mr, Wright, I did not find confh'me.d, , . ~. I p roeeeded - to tLll c)pper caps, as I had done wi~h tt)e althou-h t uetonatLng silver, which all ignited the charge. I l l . I also submitted to efperiment the fi;st-natued miXture, principally consisting o~" chlorate of potash~ and found I. T h a t it exploded only by a hard blow. Its ett~cts were much !ess than those of the detonati]~g silver, or quicksilver. M r. W r i g h t , indeed, says the contrary of the latter; it seems, therefore~ t h a t I used a better k i n d of fulminating mercu,'v~ but for that Very reason [ must give the chlorate of potash the preTerence for practical use. ~, In the fire it puffed away like gunpowder. , : . , ~, T h e s u b s t a n c e remaining after the explosion is blackish anti dusty, and c o n t a i n s tess of aci'~lfly than that left by the quicksilver. Fhus, and i n d e e d fi-om all my experiments, it is evldent that it oxtdizes ~he iron less than the fulminating mercury. Moisture is al~so left by the latter'; and the charcoal left by the ~aixture of chlorate of potash~ after ki~dling a copper cap filled with it, is v e r y unimporta n t : ~ t h e r e [ b r e this mixture is p'referable as an igniting powder. This is also the reason why the manufacturers no longer use the fulminating quicksilver, f know one who makes and fills, weekly, several t h o u s a n d s of copper caps~ for which he uses the chlorate mixture, the preparation of which is both less expensive and less dangerous than that of the fulminating quicksilver. =T h e r e is another cireutustanee .'~ttending this mixture; i n fi!ling the caps, it .nateUi's detonating" silver ~vagdissolved in lime-water or solutions of the Caustic alkalies, whereby 31,~25per ccnt of oxide of silver was deposited. They produce peculiar sMts, callcd futminafe*,which explode with g'reat violence, Thesd'*salts are dissolved by nitric acid, sulphurlc acid, and aerie tteid; the silver fidminie acid contained" in them, and so difficult to be dissolved, is de~bsited; a~ld by heating a solution of fidmiaate of lime to the boiling polar, and] adding" :t motlerate quantity of nitrle acid, is deposited, 0n eo01inff, at the bottom of the vessel~ in the shape of Ionic white crystals. This aeidmaybe easily dissolved in boitillg" water; from which it crystallizes again in cooling', has a disffustlng" metallic taste, and reddens litmus paper: but. it cannot subsist of itself without eombirmtion with a metal; and ~n the samemanner as.there are prussiales of irol~, copper, silver and gold, so the fidmlnie acid eomblnes with sil-~er, quicksilver, cop[~.er, iro~, zh~c, &e. into proper fftminates~ Whleh..a~h form different combinations with the bases e. g. potash~ soda, barytesi stronttan, li~me; &e. Thus, for instance, sitvcr-fidminate of potas!t com;i~ of 35,03 parts of silver-fuhnhfie aehl and. 14,92 of potash; silver.fidmlnate of sod~, of 88,66 parts ofsit*ree-fi~lmh~ieach! and 1i,34 of alkali. When eot~llng~Berthollet's detonating" silverfi)rms granular shinln~, white crystals. One part 0f-this salt makes as violent a ~eport as three parts of Howard s (Brug'nat~lli's)folmhaatinw silver' -With msgnlesm the- s~lver-ft~tmmtc acid combine a ta two ways~ one combmatlon is?k simple decrep~tating', not detonating, insoluble powdei', Of a rosy tlnti the other foi'ms white capillary crystals, and explodes:very loudly. Ti~'e first eombinat io;l ~ a s used for the ai~aly~of thlmini¢ ~ in the.ctry :flay; ]in: wlileh the fulminating" s~tver wa.s evil,red to~nsiSt 9£3~of:~$k,~t,, 3.~:~ Of hr¢~lrog'en, ll,28 ofazofe, 9,6V3ot'earbon,a6~;41 ofsil~er; :~*::~:~"~," 7. . . . .
Manufacture of S~gar of Lead.
105
will sometimes happen that the quantity put in is douhled~hieh:I find is of no injuri'ohs consequence witli this mixturej butm{~ht endanger the person firing with the fulminating mercury, as t~e~,cap wilt burst too violently." : ": With respect to the power of igniting the charge, the different kinds of powder which I have compared are equally effectual. IV. I-submitted the mixture of chlorate-of l~otash mentioned above to the following experiments. 1. That part only ignited which was struck9 without igniting that lyin~ around it. ~. In the fire it burns away with noise. 3. I placed it in the usual way in copper caps, but could not ignite a charge with them. The cause of this may be explained by the construction of the locks, with reference to the properties of this detonatingpowder. That part of the cap situated just above the opening ot" the cylinder remains, as the blow cannot fall on it unignited, as shown by the experiment No. 1. But the communication of the ignited part with the charge, is prevented by the manner in which t|le cock strikes the cap. In guns in which such powder is used for igniting, it lies as above stated, in small balls in a conical aperture. Hero it is nearly all ignited by the striking of the cock, and must of necessity flow inwards, every other wayofescape being shu~ up. In conclusion , ~ I have to add that the method of filling the caps recommended by Mr. ~Vri~ht is not only laborious, but even dangerous. ~How are manufacturers to eml~loy that method when they have to fill several thousands a week? I have made various t~ials, and the followin~ process seems to me to be the best. Pour some adffesive solution or tincture over the powder, and mix it into a stiff"kind of liquid. Take with a brush or a stick a large drop of it, and appl,¢ it against the bottom of the cap. T his . method . . is .both quick and free from danger; whilst on filling with the dry detonatinff powder, the least careless totteh may produce an exl~losion. In order to prevent the corrosion of the cylinder, and its beeom. ing useless bv the formation of sulphuret of iron (an evil very ecruon with iron touch-holes, and caused more by the action of the gun-.powder than by that of the igniting substance,).the inside, ofthe cyhnder should be lined with a metal which will neither oxidaten0r easily combine with the ingredients of the powdei-.~[Ph//os. ~ o
Manufactureof Sugar of Lead. Tins salt is art object of considerable interest on account of the great use made of it in caliCo-priuting~ as well as in some other arts; In the calico-nrintin~, business, it is in reality one of the ,most U~,/ll preparations;~r according to the French term. which m a n y ~ the English writers wish t o ~aturalize among us, mordant, or biter-in. VoL l l I . ~ N o . ~.~F~gnRVArtv, 18~9. 14