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New process for engraving on silver, or on silvered or gilded copper
404
Mechanics, Physics, and Chemislry.
mesh, as in the old lamp, is perfectly safe, unless exposed to a current, and as no lateral current of gas, or air, can be exerted upon the flame, on account of the chimney, the lamp is perfectly safe. Aud it is found, by any artificial means, utterly impossible to pass flame through these chambers of gauze, so that it appears to be quite safe under every cir.cumstanee and condition of the mine. There are other advantages over the Davy lamp of no considerable v a l u e : - - l . It requires trimming only once a week. 2. The oil does not fall out if laid on one side. 3. It is much mor~ easily c l e a n e d . 4. The cheapest oil can be used in it. The price of the lamp will be only Ss. or 4s. more (perhaps less) than the Davv lamp; and the latter can, at a small expense, (Ss.,) be converted into the new lamp. A cast metal instead of a brass cistern can be made, by which the new lamp can be sold for even a less price than the Davy lamp. London Artizan, March, 1848.
New Process for Engraving on Silver, or on Silvered or Gilded Copper. B y M. POIT~.VIN. Some months since we published an ingenious method, discovered by M. Ni~pee de Saint Victor, of eounler-drawing designs and eugravings upon paper, glass, or metal plates. M. Poitevin has succeeded in producing plates, engraved either in relief, or in sunk lines, from which proofs may be taken. For the carrying out of this process, from two to three hours only are required. Tile engraving is first exposed to the vapor of iodine, which becomes deposited upon the black parts only. Tile iodized engraving is then applied, with slight pressure, to a plate of silver, or silvered eopper~ polished in the same manner as daguerreotype plates. The black parts of the engraving, which have taken up the iodine, part with it to the silver, whieh is eonverted into an iodide at those parts opposite to the black parts of the design, q'he plate is then put in communication with the negative pole of a small battery, and immersed in a saturated solution of sulphate of copper, connected with the positive pole by means e r a rod of platinum. The copper will only be deposited on the non-iodized parts, corresponding to the white parts of the engraving, of which a perfect representation will thus be obtained ;--the copper representing the white parts, and the iodized silver the blaek parts. The plate must be allowed to remain ill the bath for a very short time only; for, if left too long, the whole plate would become covered with copper. The plate, after having reeeived the deposit of copper, must be earefiflly washed, and afterwards immersed in a Solution of hyposulphim of soda, to dissolve tile iodide of silver, which represents the black parts; it is then well washed in distilled water, and dried. The next operation is, to heat a plate to a temperature sufficient to oxidize the surface of the copper, which successively assumes different tints, the heating being stopped whQn a dark brown color is obtained. It is then allowed to cool, and the exposed silver is amalgamated,~the plate being slightly heated, to facilitate the operation, As the mercury
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On Pseudoquina, a New ~ql/+:aloid.
405
will not combine with the oxide of copper, a desigtt is produced, of which the amalgamated parts represent tl~e black, and the parts of the plate covered with oxide of copper, repre.++ent the white pa~'ts. The amalgamation beilag completed, dae plate is to be coverlid with three or four thickt~esses of gold leaf; alld the mercury is evaporated by heat, the gold only adhering to the black parts. The superfluons gold must then be cleaned off with the scratch-brush; after which, the oxide of copper is dissolved b y a sohtdou of nitrate of silver, and the silver and copper underneath are attacked with dilute nitric acid. Those parts of the design which are protected by the gold, not being attacked, correspond to the black parts of the plate; the other parts corresponding to the white parts of the engraving, may be sunk to any required depth. W h e n this operatio~l is completed, the plate is finished, and may be printed from in the ordinary method of printing fi'om wood-cuts. To obtain, from the same prints, p[,~tes with sunk lines, similar to the ordinary engraved copper plates, a plate of copper, covered with gold, is operated upon. On immersion in the sulphate of copper solution, the parts corresponding to the white parts will become covered with copper. The iodine, or compound of iodine, formed, is then to be removed by the hyposulphite, the layer of deposited copper is oxidized, and the gold amalgamated, which m a y be removed by means of nitric acid,--the oxide of copper being dissolved at the same time. In this instance, the original surface of the plate corresponds to the white parts of the print, and the sunk or engraved parts to the black parts, as ira the ordinary copper-plate engravings.--Bullelin de la ,7oc(~l~ a'E~couragemenl. Lond. Journ. Arts, Sept. 1848.
On Pseudoquina, a New dlkaloid.
B y M. MENGARDUO..UE.
M. Pelouze had iu his laboratory an extract of cinchona, the source of which, was uncertain ; he gave it to the author for examination as an exercise. This substance was of a deep brown color, friable, very bitter, siightly soluble in water, soluble in acids, which it saturated like the alkaLoids, and fbrmed true saline solutions, from which water precipitated it as a pitcl~y mass. This matter, treated by the processes for the extraction of.quina and cinehonia, did not yield the least trace of either of these alkaloids; nor was the einehovatine of M. Manzine met with iu it; but the author was so fortunate as to discover an alkaloid which he believes to be new, and which he so described, as to leave no doubt in the mind of M. Pelouze, who witnessed his experiments. This alkaloid differs from the substances by which it is accompanied in the extract, in saturating acids more perfectly, insomuch that it expels ammonia from its eomponnds, like lime or barytes; it scarcely dissolves, even in boiling ether, and of these properties advautagc~ was taken, in order to effect its separation. The extract was boiled with an equal weight of hydroehlorate of ammonia, till ammonia ceased to be evolqed. 0tt cooling, a very abmldaut brown matter was deposited, of a syrupy eonsistenee~ upon which
Mechanics, Physics, and Chemislry.
mesh, as in the old lamp, is perfectly safe, unless exposed to a current, and as no lateral current of gas, or air, can be exerted upon the flame, on account of the chimney, the lamp is perfectly safe. Aud it is found, by any artificial means, utterly impossible to pass flame through these chambers of gauze, so that it appears to be quite safe under every cir.cumstanee and condition of the mine. There are other advantages over the Davy lamp of no considerable v a l u e : - - l . It requires trimming only once a week. 2. The oil does not fall out if laid on one side. 3. It is much mor~ easily c l e a n e d . 4. The cheapest oil can be used in it. The price of the lamp will be only Ss. or 4s. more (perhaps less) than the Davv lamp; and the latter can, at a small expense, (Ss.,) be converted into the new lamp. A cast metal instead of a brass cistern can be made, by which the new lamp can be sold for even a less price than the Davy lamp. London Artizan, March, 1848.
New Process for Engraving on Silver, or on Silvered or Gilded Copper. B y M. POIT~.VIN. Some months since we published an ingenious method, discovered by M. Ni~pee de Saint Victor, of eounler-drawing designs and eugravings upon paper, glass, or metal plates. M. Poitevin has succeeded in producing plates, engraved either in relief, or in sunk lines, from which proofs may be taken. For the carrying out of this process, from two to three hours only are required. Tile engraving is first exposed to the vapor of iodine, which becomes deposited upon the black parts only. Tile iodized engraving is then applied, with slight pressure, to a plate of silver, or silvered eopper~ polished in the same manner as daguerreotype plates. The black parts of the engraving, which have taken up the iodine, part with it to the silver, whieh is eonverted into an iodide at those parts opposite to the black parts of the design, q'he plate is then put in communication with the negative pole of a small battery, and immersed in a saturated solution of sulphate of copper, connected with the positive pole by means e r a rod of platinum. The copper will only be deposited on the non-iodized parts, corresponding to the white parts of the engraving, of which a perfect representation will thus be obtained ;--the copper representing the white parts, and the iodized silver the blaek parts. The plate must be allowed to remain ill the bath for a very short time only; for, if left too long, the whole plate would become covered with copper. The plate, after having reeeived the deposit of copper, must be earefiflly washed, and afterwards immersed in a Solution of hyposulphim of soda, to dissolve tile iodide of silver, which represents the black parts; it is then well washed in distilled water, and dried. The next operation is, to heat a plate to a temperature sufficient to oxidize the surface of the copper, which successively assumes different tints, the heating being stopped whQn a dark brown color is obtained. It is then allowed to cool, and the exposed silver is amalgamated,~the plate being slightly heated, to facilitate the operation, As the mercury
%Id.X~,I.*'~!'~V,M);r, Phih'VL /Y,H/ LJ'>',..'IIM~I
Fi.v.L
H, I ~Et' ±_,~.o
/'hlzt r,/'l;l/l~
/,~
..~-
~
-
-
.s
J
/t" J Piy. 6.
F
On Pseudoquina, a New ~ql/+:aloid.
405
will not combine with the oxide of copper, a desigtt is produced, of which the amalgamated parts represent tl~e black, and the parts of the plate covered with oxide of copper, repre.++ent the white pa~'ts. The amalgamation beilag completed, dae plate is to be coverlid with three or four thickt~esses of gold leaf; alld the mercury is evaporated by heat, the gold only adhering to the black parts. The superfluons gold must then be cleaned off with the scratch-brush; after which, the oxide of copper is dissolved b y a sohtdou of nitrate of silver, and the silver and copper underneath are attacked with dilute nitric acid. Those parts of the design which are protected by the gold, not being attacked, correspond to the black parts of the plate; the other parts corresponding to the white parts of the engraving, may be sunk to any required depth. W h e n this operatio~l is completed, the plate is finished, and may be printed from in the ordinary method of printing fi'om wood-cuts. To obtain, from the same prints, p[,~tes with sunk lines, similar to the ordinary engraved copper plates, a plate of copper, covered with gold, is operated upon. On immersion in the sulphate of copper solution, the parts corresponding to the white parts will become covered with copper. The iodine, or compound of iodine, formed, is then to be removed by the hyposulphite, the layer of deposited copper is oxidized, and the gold amalgamated, which m a y be removed by means of nitric acid,--the oxide of copper being dissolved at the same time. In this instance, the original surface of the plate corresponds to the white parts of the print, and the sunk or engraved parts to the black parts, as ira the ordinary copper-plate engravings.--Bullelin de la ,7oc(~l~ a'E~couragemenl. Lond. Journ. Arts, Sept. 1848.
On Pseudoquina, a New dlkaloid.
B y M. MENGARDUO..UE.
M. Pelouze had iu his laboratory an extract of cinchona, the source of which, was uncertain ; he gave it to the author for examination as an exercise. This substance was of a deep brown color, friable, very bitter, siightly soluble in water, soluble in acids, which it saturated like the alkaLoids, and fbrmed true saline solutions, from which water precipitated it as a pitcl~y mass. This matter, treated by the processes for the extraction of.quina and cinehonia, did not yield the least trace of either of these alkaloids; nor was the einehovatine of M. Manzine met with iu it; but the author was so fortunate as to discover an alkaloid which he believes to be new, and which he so described, as to leave no doubt in the mind of M. Pelouze, who witnessed his experiments. This alkaloid differs from the substances by which it is accompanied in the extract, in saturating acids more perfectly, insomuch that it expels ammonia from its eomponnds, like lime or barytes; it scarcely dissolves, even in boiling ether, and of these properties advautagc~ was taken, in order to effect its separation. The extract was boiled with an equal weight of hydroehlorate of ammonia, till ammonia ceased to be evolqed. 0tt cooling, a very abmldaut brown matter was deposited, of a syrupy eonsistenee~ upon which