584 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



parts; calcined gypsum powder, from 10 to 20 parts; com- 

 mon alum, from 1 to 5 parts; copperas (green), from 1 to 5 

 parts ; and sulphuric acid, from 1 to 5 parts. This prepara- 

 tion is calculated to fix the ammonia of the night-soil and 

 prevent its escape, thereby deodorizing the mass effectually. 

 The composition is to be prepared beforehand and kept in 

 large quantities, and used as required. Other substances, such 

 as blood, or offal of any kind, may also be treated with it. 

 18 A, July 5, 1872, 397. 



DETERMINATION OF ARSENIC IN WALL-PAPER. 



To ascertain whether wall-paper is colored with any arseni- 

 ous substance, the following test may be employed. A piece 

 of the paper is impregnated with a solution of nitrate of soda 

 in a mixture of water and alcohol, and dried. The dried piece 

 is burned, and the resulting ashes moistened with a lye of 

 caustic potash, previously boiled and filtered. The filtrate is 

 acidulated with sulphuric acid, and permanganate of potash 

 added until a portion of it remains unchanged. After filter- 

 ing again and cooling, some sulphuric acid and a piece of 

 pure zinc are added, and the solution placed in a closed vial 

 containing two slips of test-paper, one of which is impregnated 

 with a solution of nitrate of silver and the other with acetate 

 of lead. The presence of arsenic is indicated by the blacken- 

 ing of the nitrate of silver paper. 8 C, 1872, 195. 



ACTION OF VARIOUS SALTS ON LEAD. 



It is well known that the presence of certain salts in water 

 greatly diminishes its solvent action on lead ; and for the 

 purpose of determining the possible effect of such solutions 

 upon cisterns and water-pipes, an English chemist suspended 

 pieces of bright lead, having a known area, in various solu- 

 tions, for different periods of time, and the amount of lead 

 dissolved was estimated by the most accurate method of color- 

 tests. A critical examination of the tabulated results shows 

 that solutions containing nitrates, and especially ammonium 

 nitrate, exert the greatest solvent power, w T hile the carbon- 

 ates have the greatest protecting power; and next to them 

 the sulphates, so that a water containing the latter, even if a 

 considerable amount of nitrates be present, has not a very 

 marked solvent action on lead. 1 A, June 14, 1872, 283. 



