Chemical Science, 493 



16. Peroxide of Potash from Nitre, — Mr. Phillips decomposed 

 nitre by heat, and found the last gaseous products nearly pur6 

 azote. Upon pouring water into the gun-barrel to remove the 

 potash, he foutid that oxygen gas was immediately evolved, and in 

 such quantity that an ignited stick Was instantly inflamed, and 

 the combustion continued for a considerable period.— -PM. Mag. 

 N. S. i. p. 312. 



17. Crystallized Carbonate of Potash, — Mr. Phillips finds thid 

 salt to be composed of 



1 atom of dry carbonate of potash . . 70 



2 do. water . . . . . 18 



88 

 — Philosophical Mag. \. 469. 



18. Sulphates of Manganese and Soda. — M. Gfeiger has folttitl 

 two double salts in the residue left during the preparation of chlo- 

 rine. They are composed of sulphuric acid, oxide of manganese, 

 and soda. The sulphate of manganese and sulphate of soda are 

 in equal proportion in both : but oile contains five parts of water, 

 and effloresces in dry air ; whilst the second contains only two 

 parts, and is not altered in a similar situation: both salts deli- 

 quesce in moist air.-^—Bnll. Univ. C. x. 117. 



19. Composition of White Copper^ or Packfong. — M. Gersdorf, 

 of Vienna, says, that the proportions of the metals in this alloy 

 should vary according to the uses for which it is destined. When 

 it is to be used to replace silver, it should be composed of 25 parts 

 nickel, 25 zinc, and 50 of copper. An alloy more proper for rolling 

 consists of 25 of nickel, 20 of zinc, and 60 of copper. Cast pieces, 

 such as candlesticks, bells, &c., are to be made of an alloy com- 

 posed of 20 parts nickel, 20 zinc, 60 copper, to which 3 of lead 

 have been added. An addition of 2 or 2 1 of iron or steel renders 

 the packfong much whiter, but at the same time harder and more 

 brittle. — Annal. fur Phys. 



20. Method of Bronzing Tin, by M. Verly. — ^To obtain complete 

 success in bronzing medals of tin, the two following solutions must 

 be ertiployed : the first, which is merely a wash, is composed of 1 

 part of iron, 1 part of sulphate of copper, and 20 parts, by weight, 

 of distilled water. The second solution (or bronze) is composed of 

 4 parts of verdigris atid 16 parts of white vinegar. The medals 

 should be filed, and well cleaned with a brush, earth, and water ; 

 and, being well wiped, should have a portion of the first solution 

 passed lightly over their faces, by means of a brush, and then be 

 wiped ; this gives a slight grey tint to the surface, and causes the ready 

 adhesion of the verdigris, &c. The second solution is then to be 



