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Action of ammoniacal salts on glass
330 Progress of Practical ~. Theoretical ~rechanics ~. Chemistry. hydrochloric acid, with heatLin a small gas bottle.. H y d r o g e n gas escapes, which will not inflame immediately on account ot the v a p o u r of w a t e r and acid with which it is mixed. Collect it in a tube filled with w a t e r , and fur:fished with a stop cock, or otherwise connected with a pointed tube. Inflame the gas, and let the burning jet play against a piece of cold porceIain,--the arsenic, if any be present, will be deposited, as is well known, in the torm of a black shining coating, n,,~
Action of dmrnoniacal Salls on Glass. B y M.M.,.rtcrtA~r). Pog, t. 4~.)
(dtnn. de
Mixtures of hydrochlorate and nitrate of ammonia attack glass very strongly, especially when it contains lead. "When sulphate of ammonia is heated in a glass vessel, it begins to melt at 140 ° , and from that to ~80 ° it undergoes no alteration; but at this temper. ature ammonia is disengaged, sulphate and sulphile of ammonia sublime, and we soon remark that the glass is strongly attacked; the interior surface becomes (lull, from a combination of sulphuric acid with the potash. T h e glass often cracks and sulphate of potash issues through the c r e v i c e s , lbi~
Hydrographic Paper. Paper is sold in Europe under the above title, on which, if one writes with water instead of ink, or even with the saliva of the mouth, the letters are black and perfectly legible. This paper is prepared by steeping common white p a p e r in a weak solu. tion or inthsion of gall nuts, and when dry rubbing over it finely powdered copperas(su]phateofiron.) It thus contains the elements necessary for the production of ink, and needs only the water necessary ior t h e i r solution. The water traced by the pen effects this union and forms a b l a c k letter.
,~dethodof JOiseovering the atdulleratiori of Wax. T h e wax of commerce is too often mixed with various substances, and especially with potatoe flour. A simple method of detecting this sophisti. cation is to melt a piece of the wax over a gentle fire, and then to dissolve it in a cerlain quantity ofspirits ofturpentine. T h e wax will entirely dissolve and the impurities be left behind, and by knowing the w e i g h t o f the wax and ascertaining that of the sediment, the amount of the adulteration can easily be ascertained. The colour given to wax does not~ in general, injure its quality, but merely gratifies the eye of the purchaser.
:Deposition of ~loislure on ll~Ielala. By M. BO~SDoRFIf we place, in an atmosphere saturated with humidity, a piece o f polished zinc and a piece of tarnished lead in contact, when the t e m p e r a t u r e lowers ~he lead becomes covered with dew, and the zinc remains d r y without oxydizing. It is thus with two different metals. T h e moisture settles on one only. I f the effect be attributed to electricity we must c o n c l u d e that the droplets are electrified positively, ib~
Action of dmrnoniacal Salls on Glass. B y M.M.,.rtcrtA~r). Pog, t. 4~.)
(dtnn. de
Mixtures of hydrochlorate and nitrate of ammonia attack glass very strongly, especially when it contains lead. "When sulphate of ammonia is heated in a glass vessel, it begins to melt at 140 ° , and from that to ~80 ° it undergoes no alteration; but at this temper. ature ammonia is disengaged, sulphate and sulphile of ammonia sublime, and we soon remark that the glass is strongly attacked; the interior surface becomes (lull, from a combination of sulphuric acid with the potash. T h e glass often cracks and sulphate of potash issues through the c r e v i c e s , lbi~
Hydrographic Paper. Paper is sold in Europe under the above title, on which, if one writes with water instead of ink, or even with the saliva of the mouth, the letters are black and perfectly legible. This paper is prepared by steeping common white p a p e r in a weak solu. tion or inthsion of gall nuts, and when dry rubbing over it finely powdered copperas(su]phateofiron.) It thus contains the elements necessary for the production of ink, and needs only the water necessary ior t h e i r solution. The water traced by the pen effects this union and forms a b l a c k letter.
,~dethodof JOiseovering the atdulleratiori of Wax. T h e wax of commerce is too often mixed with various substances, and especially with potatoe flour. A simple method of detecting this sophisti. cation is to melt a piece of the wax over a gentle fire, and then to dissolve it in a cerlain quantity ofspirits ofturpentine. T h e wax will entirely dissolve and the impurities be left behind, and by knowing the w e i g h t o f the wax and ascertaining that of the sediment, the amount of the adulteration can easily be ascertained. The colour given to wax does not~ in general, injure its quality, but merely gratifies the eye of the purchaser.
:Deposition of ~loislure on ll~Ielala. By M. BO~SDoRFIf we place, in an atmosphere saturated with humidity, a piece o f polished zinc and a piece of tarnished lead in contact, when the t e m p e r a t u r e lowers ~he lead becomes covered with dew, and the zinc remains d r y without oxydizing. It is thus with two different metals. T h e moisture settles on one only. I f the effect be attributed to electricity we must c o n c l u d e that the droplets are electrified positively, ib~