220 DETECTION OF ARSENIC IN ORGANIC MIXTURES. 
action of acids or an elevated temperature, both acquire 
under the same circumstances a very marked brownish-red 
colour. From these facts it follows, that if the cane or beet- 
root sugar submitted to evaporation contains at the same 
time glucose, or modified cane-sugar and lime, the product 
will necessarily be coloured ; this is precisely what hap- 
pens daily in practice. Now I propose to avoid this serious 
inconvenience by means of the oxalate of alumina. It 
suffices for this purpose to add to the saccharine solution 
containing lime a suitable quantity of hydrated oxalate of 
alumina; the lime is immediately precipitated in the state 
of oxalate, and the alumina set free subsides in its turn, 
carrying with it in combination all the colouring matter ex- 
isting in the mixture — a twofold advantage, the value of 
which will be readily appreciated. — Chem. Gaz. from 
Comptes Rendus. 
ART. LXVII.— NEW PROCESS FOU THE DETECTION OF 
ARSENIC IN ORGANIC MIXTURES. 
By H. Letheby, M. B. 
The author found that Reinsch's process was neither 
certain nor delicate ; it was true that the copper would 
withdraw every and the smallest trace of arsenic ; but when 
this quantity was minute, it was by no means easy to 
detect it afterwards. The author, therefore, reflecting upon 
these circumstances and upon the exceeding delicacy of 
Marsh's test, was led to believe that if some other metal 
were used, which like copper not only had the faculty of 
withdrawing the poison, but would also serve for the gene- 
ration of hydrogen, he might be able to combine theadvan- 
