Proceedings of the Polytechnic Association. 955 



Contamination by Zinc Tanks. 

 M. Zinrek calls attention, in Dingler's Polytechnic Journal, to the 

 fact that water, kept in small reservoirs made of zinc or collected 

 from roofs covered with zinc, is invariably contaminated with that 

 metal, and that the use of such water for domestic purposes is highly 

 injurious to health. The author recommends that where zinc vessels 

 are used for the purpose indicated they should be painted over with 

 asphalt varnish or any iron pigment. 



Utilization or Leathek Scraps. 

 The Paris Cosmos states that a material which can be pressed into 

 the form of combs, buttons, knife-handles, etc., may be made from 

 leather scraps by cutting them into small pieces and keeping them 

 for several days in chloride of sulphur; in this way they become 

 hard and brittle. After being washed they are dried, ground to 

 powder, and mixed with glue, or a solution of gum-arabic, or any 

 other adhesive substance, when the mixture is ready for the moulds. 

 Dr. D. D. Parmelee remarked that this substance containing glue or 

 gum-arabic could not be water-proof. 



DiATIL. 



This name is given by J. M. Merrick to a plastic mass which he 

 obtains by mixing equal parts of gum lac and tinely divided sili^. 

 In order to obtain a perfectly homogeneous composition, the mass is 

 pressed between rollers, heated by steam, like those employed in 

 India-rubber factories. While hot it can be moulded into any form. 

 It is preferable to " artificial wood," because it does not absorb moist- 

 ure. Medals made of this composition have, great sharpness and 

 luster. The silica is prepared by precipitating it from the silicate of 

 potash. 



Antidotal Power op Phenol. 



Mr. Schiffuian writes from Yalle-Menier, Nicaragua, to the 

 Moniteur Scientific of Paris, that after a very severe epidemic of 

 Asiatic cholera which caused, during fifteen months, the death of a 

 large number of people, he commenced the use of phenol or carbolic 

 acid, causing all the rooms and passages of the houses occupied by 

 300 people to be daily sprinkled with water containing a small 

 quantity of this acid, with the result that neither cholera nor fever 

 and ague, which had long pestered that locality, had since made 

 their appearance. 



