72 FALLACY OF DR. BIRKBECK NEVINS' TEST. 
ART. XVIII.— FALLACY OF DR. BIRKBECK NEVINS' TEST 
FOR ASCERTAINING THE PURITY OF DISULPHATE OF 
QUININE.— By G. M. Mowbray. 
The following test has been suggested by Dr. Birkbeck 
Nevins, as appropriate for readily ascertaining the purity of 
disulphate of quinine. 
" To one or two grains of the suspected salt add three 
or four drops of sulphuric acid in a white evaporating dish 
and twice as many drops of water ; if the salt contains either 
starch or fatty matters they will remain, whilst if they are 
absent the whole will be dissolved. Let heat be next ap- 
plied to the solution, and as it becomes concentrated, the 
acid will char any sugar which may be present, which will 
be indicated by a black stain round the edge of the solution, 
and the whole will speedily assume the same color." 
Allow me to submit, that this test is valueless, and for the 
following reasons : Dr. Nevins appears to have overlooked 
a fact well known to chemists whose investigations have 
been directed to organic compounds, that salts may be 
readily recognised as belonging either to the organic or in- 
organic class, by heating on platina : if the compound under 
examination, after heating, yield a carbonaceous residue, 
then it belongs to the former class ; if a whitish ash be left 
after ignition, then an inorganic compound has been acted 
upon. Now, Dr. Nevins directs us to add sulphuric acid 
to the disulphate ; the effect of this is to convert the salt into 
the soluble sulphate, and on the application of heat, this 
soluble sulphate, in common with all organic salts, is decom- 
posed, yielding a carbonaceous residue. 
Could Dr. Nevins have shown, that which is opposed to 
all experimental results with organic compounds, that in the 
presence of sulphuric acid quinine is not readily carbonized 
— and the reverse of this is the fact, as may readily be as- 
certained by heating a crystal of the soluble sulphate by 
the side of a sample of quinine purposely adulterated with 
sugar or gum — his test might be so far admissible. ; but as 
Dr. Nevins has not shown this, and it cannot be shown 
withal, therefore his test is fallacious. — Med. Gazette, 
