1870.] Chemistry. 107 



while at the same time a current of dry hydrogen gas is passed 

 through, phosphide of zinc is formed. From the phosphide of zinc 

 so obtained, phosplmretted hydrogen may be readily prepared by 

 means of dilute sulphuric acid, or by boiling with caustic potash. 



A method of strengthening and rendering woven tissues imper- 

 meable to water has been invented by M. Newman. A sulphuric 

 acid bath is made containing acid of about 1 ' 6 specific gravity, and 

 kept at a temperature of 57°. The woven tissues, cotton or linen, 

 are rapidly passed through this bath, being only left in contact 

 with the acid for from ten seconds to two minutes, according to the 

 nature of the tissue, which is immediately after passed through 

 very cold water, and next submitted to a thorough washing process. 

 The effect of the action of the acid is the formation of a varnish-like 

 matter, which, especially after it has been regularly spread over the 

 fabric and incorporated therewith by hot-pressing and calendering, 

 greatly increases the strength of the fabric, and renders it simulta- 

 neously impervious to water. 



The manufacture of oxygen gas on a commercial scale is 

 increasing in Paris; Mr. Fowler, who has described one of the 

 factories, says that 500 pounds of manganate of soda, furnish 2J 

 cubic yards of oxygen every hour. This charge is placed in a 

 retort and superheated, steam passed over it ; in five minutes all 

 the oxygen is extracted from this quantity of the salt. Hot air 

 passed over this residue for five more minutes restores all the oxygen 

 given up, and the result of an hour's continuous work, or six extrac- 

 tions of oxygen and six re-oxidations, is 2 j- cubic yards of oxygen. 

 This oxygen, when it issues from the gasometers, contains about 

 15 per cent, of nitrogen, but by letting the first portions escape, 

 the quantity of this mixture can be reduced to 2J per cent. 

 M. Tessie du Mothay affirms that one ton of manganate of soda 

 will yield 100 cubic yards of oxygen daily, or more than 36,000 per 

 year ; and this without having to renew the salt once. 



According to M. Kessler, when burning magnesium wire is 

 placed in a vessel containing carbonic acid, the latter is decomposed, 

 and carbon deposited. Some nitric acid should be poured into the 

 vessel at the end of the reaction in order to dissolve the magnesia 

 resulting from the combustion, and to make the deposit of carbon 

 distinct. Water having been poured in a rather wide-mouthed flask, 

 it is made to boil as briskly as possible ; when, after this boiling 

 has been continued for some time, previously-ignited magnesium 

 wire is held deep down in the mouth of the flask, it continues to 

 burn. The same metal burns with great brilliancy in nitrous and 

 nitric oxide, also in sulphuretted hydrogen and sulphurous acid, but 

 is extinguished by carbonic oxide. 



Dr. Poselger deserves the thanks of the public for his determin- 



