558 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



solution of the silicate was found to destroy all the micro- 

 scopical bodies in animals or vegetables, which seem to be as- 

 sociated with the propagation of infectious diseases. It takes 

 hold of and solidifies the mucilage, gum, mucus, and albumen 

 of the organic liquids. It also protects the surfaces against 

 the absorption of poisonous external agents, renders suppu- 

 rations wholesome, and neutralizes the infectious elements of 

 cutaneous diphtheritis, so apt to follow the application of 

 blisters in crowded hospitals. It also has a very happy ef- 

 fect in the treatment of ulcerous chronic diarrhoea. 6 B^ 

 Mbrucny 10,1813,34.3. 



ADULTERATION OF BONE-DUST BY VEGETABLE IVORY. 



It has been ascertained that the powder of the vegetable 

 ivory-nut is used very largely for the adulteration of bone- 

 dust, being so similar as to be very difficult of distinction. 

 Even the microscope scarcely furnishes a satisfactory means 

 of determining the facts in the case, especially if the external 

 envelope of the fruit has been carefully removed. The best 

 method, however, short of chemical analysis, is said to con- 

 sist in throwing the suspected substance upon hot coals. If 

 vegetable ivory be present, a pleasant odor, like that of roast- 

 ed coffee, will be immediately diffused, while bone-dust yields 

 a disagreeable animal odor. The precise proportion" of the 

 two substances can only be determined by chemical analysis. 



ELECTRO-STANNUS METHOD OE PLATING. 



A recently invented mode of plating, known as the electro- 

 stannus process, consists in the use of a cheap Avhite metal, 

 of which tin is the principal ingredient, and which can be 

 readily deposited galvanically upon all metals excepting 

 zinc. The articles to be plated are first thrown into a bath 

 of weak sulphuric acid and water, and then into a second 

 strong bath of boiling potash lye, when a complete chemical 

 cleanness is effected. They are then suspended in a vat con- 

 taining a solution of metal, and, having remained there a suf- 

 ficient length of time, they are " scratched " by a rajjidly re- 

 volving wire brush, when they are ready to return to the 

 customer. 



In emerfrimr from the vat, the articles are of a dull leaden 

 color; but they are susceptible of a high polish, very little 



