ARSENIATED HIDROGEN GAS. 20l 



Pfouft is the only philofopher who mentions this gas : * he Prouft mentions 

 obtained it by digefting arfenious acid and zinc, in dilute ful- '^' 

 phuricacid; on burning the gas, he obtained ibmetimes arfe- 

 nious, at -Others arfenic acid. Being perfuaded that the for- 

 mation and properties of this gas deferved a clofer examination, 

 I inftituteda feries of experiments, the refults of which are as 

 follows. 



Methods of obtaining arfiniated Hidrogen Gas. 



1. There are a variety of procefles for obtaining arfeniated Proceflesforobv 

 hidrogen. It is produced by heating tin filings in liquid arfe- ated'hfdro^'^eT 

 nic acid. This method is the moft expenfive and moft tedious, gas. 

 During the evolution of the gas in this procefs, arfenic, al- 

 loyed with tin, is precipitated, and the fluid obtained, holds in 



folution, arfeniate of tin. 



2. It is likewife formed by treating in a fimilar manner, arfe- 

 nic and iron with muriatic acid. 



3. Arfeniated hidrogen is alfo produced by heating a mix- 

 ture of arfenious acid, iron filings and muriatic acid. The 

 fluid, in this cafe, contains muriate of iron and muriate of 

 arfenic. 



4. Tin filings and arfenic acid yield this gas under fimilar 

 circumftances. 



5. Four parts of granulated zinc and one of arfenic, treated 

 in a fimilar manner with fulphuric acid, prevloufly diluted with 

 two parts of water, afford arfeniated hidrogen very readily. 



The gas obtained according to either of thefe proceflies, is Beft produce* 

 nearly alike, but that produced according to the laft procefs ^'^°™.J'"^*^^»j 

 feems to be the moft perfed gas, for It contains no excefs of fulphuric add. 

 hidrogen. When arfeniated hidrogen is produced by means 

 of zinc, arfenic, and dilute of fulphuric acid, the quantity 

 of arfeniated hidrogen is lefs than the quantity of hidrogen 

 which would be obtained in decompofing water In a fimilar 

 manner, without the interpofition of arfenic. The refidue, 

 after the evolution of the gas has ceafed, contains metallic arfe- 

 nic; part of the hidrogen muft therefore have a6led on the 

 oxigen of the arfenic acid, in order to reduce it to the metal- 

 lic ftate. From what has been ftated, it appears that arfeni- 

 ated hidrogen contains arfenic in a metallic ftate, and not in 

 the ftate of arfenious, or arfenic acid. This will become more 

 obvious in the fequel of this paper. 



* Journ.de Phys. T. II. p. 173. 



Fhyftcal 



