N. MATEKIA MEDICA, THERAPEUTICS, AND HYGIENE. 641 



are the best destructives of the active properties of vaccine 

 lymph, and therefore are more likely to act upon variolous 

 matter and other zymotic substances. 18 ^, J/ay 16, 1873, 

 209. 



POISONOUS CHAKACTEE OF METHYLAMilONIUM COMPOUNDS. 



Rabuteau has ascertained that the iodide of methylam- 

 moniuni and the iodide of tetramylammonium act upon ani- 

 mals precisely like the curare poison, by destroying motions 

 without affecting the sensibility, and with precisely the same 

 subtility and energy. A few centigrammes will kill a dog in 

 a few minutes. 3 J?, ^^:>?77 10, 1873, 621. 



ACTION OF WATER ON LEAD PIPES. 



Sir Robert Christison, who has devoted much attention to 

 the influence of water upon lead in passing through pipes, etc., 

 has ascertained that the purest waters are those which act 

 most powerfully upon lead, corroding it, and forming a car- 

 bonate of a peculiar and uniform composition, and that all 

 salts impede this action, many preventing it altogether, some 

 of them doing so when in extremely minute proportions. 3 

 A, May 31, 1873, 615. 



DETECTION OF ARSENICAL COLORS IN PAPER, ETC. 



H. Hagar gives the following process for detecting arsen- 

 ical color in paper. A piece of the paper is soaked in a con- 

 centrated solution of nitrate of soda in a mixture of equal 

 volumes of alcohol and water, and allowed to dry, and then 

 burned in a flat porcelain capsule. The ashes are covered 

 w4th water, several drops of caustic potash solution are add- 

 ed, so as to produce a strong alkaline reaction, then heated to 

 boiling, and filtered. Permanganate of potash is gradually 

 added to the warmed filtrate, previously acidified with dilute 

 sulphuric acid, as long as decoloration, or conversion of the 

 red to a yellowish-brown color, takes place; and finally a 

 slight excess of the permanganate is introduced. If the liquid 

 become turbid in the operation, it must be filtered. After 

 cooling, and the addition of more dilute sulphuric acid, a piece 

 of pure zinc is added, and the flask closed with a cork with 

 two splits in it, in one of which a strip of parchment paper 

 moistened with nitrate of silver is fastened, and in the other 



