116 



CHEMISTRY. 



plishing the same object consists in making 

 the gases which have traversed the ordinary 

 Gay-Lussac tower afterward traverse several 

 supplementary towers, supplied with weaker 

 sulphuric acid than is supplied to the Gay- 

 Lussac tower itself. 



Domestic Chemistry. F. P. Hall, of the Mas- 

 sachusetts Institute of Technology, has pub- 

 lished in the "American Chemical Journal" 

 the results of some investigations on the cor- 

 rosion of fruit-cans and tin-foil by the acids of 

 the articles of food inclosed in them. Acetic, 

 tartaric, and citric acids dissolved more tin 

 and lead (in some cases twice as much) from 

 sheets of pure metal than from alloys. In 

 glass-stoppered bottles from which the air was 

 as well excluded as it is from ordinary fruit- 

 cans, the action was less than in loosely- cov- 

 ered beakers, but still considerable. Three 

 cans tli at had been emptied were let stand 

 two weeks with acid in them, at the end of 

 which time the tinning had been taken off up 

 as far as the acid reached. There was dis- 

 solved by 



Hence a can once opened should be emptied 

 immediately, as corrosion thereafter takes place 

 very rapidly. Analyses of the " bright plate " 

 of which cans and other tinware are made, 

 showed no admixture of lead in the tinning, 

 and no tinware could be found made of "terne 

 plate," the sort that is understood to be coated 

 with an alloy of tin and lead. The solder of 

 the cans, however, contains a large amount of 

 lead, and vegetable acids act on this as well as 

 on the pure tin of the plate. 



Twelve specimens of tin-foil obtained from 

 dealers were analyzed. Only threfe of these 

 were sold for pure tin, and they proved to be 

 as represented; the others, some of which 

 were called ** composition foil," gave from 60 

 to 95 per cent, of lead. Nine specimens that 

 had been in use gave various results. Two 

 from different kinds of compressed yeast con- 

 tained no lead, and a piece of foil from a cake 

 of chocolate bought at a street stand was also 

 pure. A piece of embossed foil from a fancy 

 cake of chocolate gave 80 per cent, of lead, 

 and in two specimens from Neufchatel cheese 

 were found respectively 73-19 and 75-27 per 

 cent. " The use of a foil containing about 75 

 per cent, of lead for wrapping the so-called 

 Neufchatel and other soft cheese is certainly 

 reprehensible. Owing to the acid in or de- 

 veloped in the cheese, the foil becomes crum- 

 bly, and even when the cheese is first covered 

 with greased paper, particles of the oxidized 

 foil are very likely to become attached to the 

 cheese as it is used." 



Mr. William Thomson, F. E. S. E., having 

 investigated a case of lead-poisoning arising 



from the use of unsuspected water-pipes of 

 lead, was induced to examine the merits of 

 the tin-lined pipes. A pipe, the coating of 

 which was from -j^ to -fa of an inch thick, 

 to his surprise, gave evidence of contamina- 

 tion to the water that passed through, and 

 the lining was found to contain a large 

 proportion of lead. A similar pipe from an- 

 other manufactory revealed the same impu- 

 rity. These pipes were found to have been 

 made by pouring tin down the side of a strip 

 of lead in introducing it as lining. In the 

 course of the process the tin had dissolved a 

 considerable quantity of lead. Such pipes are 

 used to a considerable extent in drawing beer, 

 and are in danger of contaminating the liquor, 

 particularly that portion of it which, standing 

 in them over night, is sold to the first customer 

 in the morning. In another kind of lead pipe, 

 called "tinned-lead pipe," the inside coating is 

 made by filling the first few inches of the lead 

 pipe, while still very hot, with molten tin, 

 which remains molten and washes the inner 

 surface of the lead tube as it is produced. The 

 quantity of this " tin " increases as the pipe is 

 drawn out, by melting the lead with which it 

 is in contact and carrying it along, and ulti- 

 mately the lining consists chiefly of lead. Mr. 

 Thomson has observed that aerated waters are 

 contaminated with lead much more often and 

 in many cases to a much greater extent than 

 would be expected, considering the pains which 

 is taken in preparing the articles. Manufac- 

 turers admit the fact, but say that it is impos- 

 sible to procure the substances free from me- 

 tallic contamination at anything like reason- 

 able cost. 



M. Gustave Le Bon has been carrying on in- 

 vestigations upon the action of antiseptics, 

 from which he concludes that the disinfectant 

 power of any antiseptic appears to be the more 

 feeble as the putrefaction is the more ad- 

 vanced. If an aqueous solution containing 

 one tenth its weight of minced meat be taken 

 as the normal solution, it will exhale during 

 the first stages of putrefaction an extremely 

 fetid odor, which, however, can be destroyed 

 by a comparatively small amount of antiseptic. 

 At the end of about two months new bodies 

 with a special odor will be developed, which 

 require for their destruction quantities of the 

 same antiseptic at least twice as great as at 

 first. If the power of antiseptics be measured 

 by taking as a means of comparison their dis- 

 infectant properties upon a given weight of 

 the normal solution already mentioned, the 

 most powerful disinfectants will be shown to 

 be potassium permanganate, chloride of lime, 

 sulphate of iron acidulated with acetic acid, 

 phenol, and the glyceroborates of sodium and 

 potassium. There is no parallelism between 

 the disinfectant action of an antiseptic and its 

 action on microbes. Potassium permanganate, 

 which is one of the most powerful disinfect- 

 ants, exercises no appreciable action on mi- 

 crobes. Alcohol, which checks the develop- 



