ON ANIMAL LIFE IN WATER CONTAINING FREE ACIDS. 185 



40 ounces, and were filled about half full. It was found 

 in most cases (I might almost, indeed, say in all) that the 

 nitrate-of-silver solution was not required, the water and 

 hydrochloric acid absorbing all the arsenic which was in 

 the air drawn through. 



The idea of arsenic being present in the atmosphere 

 surrounding chemical works is by no means new. The 

 fact of its existence in large amounts in the ore from 

 which the greater amount of our vitriol is made leads 

 one to suppose that it must find its way into the atmo- 

 sphere at one place or another ; but I believe this is the 

 first time the comparative amounts have been brought 

 forward. It would be very interesting to have similar 

 analyses made on this subject in the various works where 

 large quantities of sulphur ore are burnt, so that we could 

 have an idea of the amount of this impurity which is being- 

 daily thrown into the atmosphere in the neighbourhood of 

 Manchester. 



I also made some attempts to determine the amount of 

 arsenic in grass grown close to the works at which these ex- 

 periments were carried on; but the result was very unsatis- 

 factory. The grass should be got from some distance from 

 the alkali-works, in the direction of the prevailing winds. 



XXII. On Animal Life in Water containing Free Acids. 

 By H. A. Smith, F.C.S. 



Read April 30th, 1872. 



So much has been written lately concerning animal life, 

 its origin, and the conditions under which it can origi- 



