ARSENIC FROM ALKALI-WORKS. 



181 



passes, along with a very small proportion of the uncon- 

 densed hydrochloric acid gas, to the chimney. 



A deposit in the flue (about 20 feet long) leading from 

 the salt-cake furnace to the condensing-towers, the coke 

 contained in the towers themselves, the gas in the flue 

 leading to the chimney (through which the gases pass, 

 having first passed through a small extra washing-tower), 

 and the smoke escaping to the chimney were all sub- 

 mitted to analysis, and found to contain arsenic. 



The results are gathered together in the following 

 Tables :— 



Table I. — Deposit in Flue leading from Salt-cake 

 Furnace to Condensing-towers. 



No. of analysis. 



Arsenic trioxide. 



per cent. 

 44-66 



42*93 



45'33 



39-9 8 



..... 46-45 



44-40 



4°'44 



38-97 



4773 



390-89 



Mean 43'43 



In this Table we have the results of nine analyses of a 

 deposit found in a flue leading from the reverberatory 

 furnace to the condensing-towers. The total length of 

 this flue is about 20 feet ; the part from which the dif- 

 ferent samples were taken is about 15 feet from the 

 furnace : the gas had therefore undergone cooling to a 

 certain extent. The deposit at first sight appeared to be 

 principally composed of common salt and a little sulphate 

 of soda; but on examination with an ordinary hand- 

 microscope, small octahedral crystals of arsenic trioxide 



