Manchester Memoirs, Vol. xlvii. (1903), No. \\ 



XV. Further Investigation on the Detection and 

 Approximate Estimation of Minute Quantities of 

 Arsenic in Malt, Beer, and Food Stuffs. 



By William Thomson, F.R.S.E., F.I.C. 



Received and read Alarch j7-d, igoj. 



Since my paper on this subject, read before the 

 Manchester Section of the Society of Chemical Industry 

 on the 2nd May, 1902, and published in the British Food 

 Jotirnal, Vol. IV., Nos. 44 and 45 (1902), and in the 

 Medical Chronicle for October, 1902, I have continued the 

 investigation with the view of improving on the process 

 there described for detecting and estimating minute 

 quantities of arsenic. 



Wrapping the heated portion of the tube in copper zvire 

 gaiise. 



It was recommended by the Joint Committee of the 

 Society of Chemical Industry and of the Society of Public 

 Analysts, that a piece of copper wire gauze about one inch 

 square be wrapped round the tube which receives the 

 mirror at the point at which it is heated (immediately 

 before the drawn-out portion). I directed my attention 

 to find what advantage this offered over the heating of 

 the naked glass tube, and ascertained that the use of the 

 copper wire gauze was a positive disadvantage, the mirrors 

 being less distinct with, than without, the wire gauze. 



September 2gth, igoj. 



