330 
supplied to us since 1905 ; one having the appearance of a white 
powder, the other of distinct crystals. Jt was found that the powder 
contained free inorganic arsenic (from 0*4 to 0'9%), which is easily 
detected by passing H^S into the slightly acidified solution. The 
crystalline Atoxyl did not contain any inorganic arsenic. 
P arafuchsin .— On two occasions it was noticed that the freshly 
prepared solution of Atoxyl was of a red colour ; this was due to the 
presence of parafuchsin, which is formed as a by-product during the 
preparation of the drug. 
Yellow Atoxyl .— One special supply of Atoxyl sent out to Uganda 
gave rise, in the hands of Captain A. C. H. Gray,^ on injection, to 
violent toxic symptoms and blindness. The qualitative examination 
of the drug showed that it dissolved in strong alkali (40% KOH) with 
a yellow colour ; this colour reaction has never been observed by us 
in any other sample of Atoxyl. This Atoxyl contained free 
inorganic arsenic, traces of free anilin, and a second substance which 
is probably an oxidation product of Atoxyl. It is quite possible that 
this substance may be responsible for the untoward effects. 
Therefore, it would seem advisable that Atoxyl should be tested 
with strong alkali before use. i c.c. of a 5% solution should be mixed 
with 2 c.c. of strong alkali and left standing for a few minutes, and if 
the solution shows a yellow coloration the Atoxyl should not be used 
for treatment. 
A full chemical report on the ‘ yellow Atoxyl' has previously been 
published.^ 
literature 
3- 
B. Moore, Niekenstkin and Todd. Bio-chemical Journal, Vol. II, 1907, p-JM- 
Ehrlich and Bertheim. Berichte d. deuischen chemischen GeseUschafl, 
Vol. 40, p. 3296 
^ Gray. Quarterly Report 011 the Progress of Sleeping Sickness and 
Medical Treatment of Sleepinj Sickneas in Uganda, ,go 3 . pp. 3a and 35 - 
