172 



"Corrections of the Nomenclature of the objects figured 

 in a memoir ' On some of the Minute Objects found in the 

 Mud of the Levant,' &c., published in Vol. VIII. of the Me - 

 moirs of the Literary and Philosophical Society of Manches- 

 ter/' by Professor W. C. Williamson, F.R.S. 



" On Arsenic fron) Alkali Works," by H. A. Smith, F.C.S. 

 Communicated by Professor H. E. RoscoE, F.KS. 



Some time ago the author laid before the Society the 

 results of several analyses of the amounts of arsenic con- 

 tained in different species of pyrites, and in several of the 

 products in the manufacture of which the acid was employed 

 At that time he carried his analyses as far as the carbonate 

 of soda, in which no arsenic was found. The present paper 

 is supplementary to the former, and he now endeavours to 

 to show that not onty does the arsenic remain in the 

 various products of alkali manufacture but even escapes to 

 the atmosphere. 



When the salt used for the production of Hydrochloric 

 acid is treated with Sulphuric acid, containing Arsenic, the 

 Arsenic present becomes converted into the trichloride. 

 This compound is said to be completely decomposed by 

 contact with water, so that, after passing along with Hydro- 

 chloi'ic acid gas through the condensing towers, it would 

 scarcely be expected that any traces of the Arsenic originally 

 present would be found in the escaping gas. The author 

 finds this, however, to be the case. A considerable quantity 

 of the Arsenic trichloride escapes the action of the water in 

 the condensing towers, and passes, along with a very small 

 proportion of the Hydrochloric acid gas, to the chimney. 



A deposit found in the flue, about 20 feet long, leading 

 from the saltcake furnace to the condensing towers ; the 

 coke contained in the towers themselves ; the gas in the 

 flue leading to the chimney ; and the smoke escaping to the 

 chimney were all submitted to analysis, and were all found 

 to contain arsenic. 



