Manchester Memoirs, Voi. xlviii. (1904), No. 17. 11 



tubes containing the arsenic mirrors which follow, marked 

 " without," are those produced from 50 c.c. of a solution 

 containing Tr^th of a grain of As,i06, and the next two 

 shew the same experiment repeated, but with the excep- 

 tion that 2 c.c. of amyl alcohol were put into the apparatus. 

 The mirrors produced when amyl alcohol was used with 

 this comparatively large quantity of arsenic trioxide shew 

 less than those without amyl alcohol, but the difference 

 becomes more marked as the quantity of arsenic present 

 becomes smaller. The second set of four mirrors (same 

 Plate) were made each from 50 c.c. of a solution contain- 

 ing Joth of a grain per gallon. The first two tubes were 

 obtained without amyl alcohol, and the second two with 

 2 c.c. of amyl alcohol. The mirrors are seen to be con- 

 siderably smaller in the experiments with amyl alcohol 

 than in those without it. 



In the third set 50 c.c. of solution, containing x^o^h 

 of a grain per gallon (which is the maximum which the 

 Committee recommends should be allowed in beer) were 

 used. Those without amyl alcohol show pretty strong 

 mirrors, whilst those with amyl alcohol show practically 

 no mirrors, and it must be remembered that the quantity 

 of beer recommended to be employed for this test by the 

 Committee is 25 c.c, or only one-half of the quantity 

 used in this experiment, so that it does not appear satis- 

 factory under any circumstances to permit the use of 

 amyl alcohol. 



In the fourth set of experiments 50 c.c. of a solution 

 containing g^oth of a grain of As^Oe per gallon were 

 employed (this being the actual amount of AsiOe which 

 would be present in the apparatus from a beer which is 

 recommended as the limit of As^Oe permissible in beer), 

 without amyl alcohol faint mirrors are shown, with amyl 

 alcohol no mirrors at all are produced. 



