526 
PROFESSOR A. H. CHURCH ON TURACIN, 
Turacin taken, corrected for ash , , , , '3178 grm. 
CuO obtained.. . . , '0323 ,, 
This result corresponds to 8'11 per cent, of metallic copper. But on testing the black 
oxide of copper it was found to contain calcium phosphate and traces of ii’on and 
manganese. 
© 
A sample of turacin from Musophaga violacea was examined for copper b) T Professor 
Kinch, in November, 1891, the weighed substance being incinerated with every pre¬ 
caution in a crucible with sodium carbonate and potassium nitrate. The cupric oxide 
formed was dissolved in nitric acid, and precipitated by sodium hydrate, the precipi¬ 
tate being again dissolved, to remove silica, and re-precipitated. 
The figures in this analysis were— 
Turacin taken, corrected for ash , , '1635 grm, 
CuO obtained.'0168 ,, 
This result corresponds to 8'2 per cent, of copper. 
The mean percentage of copper in turacin, as deduced from the four determinations 
last recorded is 8'03. But there is a very good reason for not accepting this figure, 
for we have no guarantee that the precipitate produced by a fixed alkali in the solu¬ 
tions of turacin ash was pure. I conclude, indeed, that in Mr. Bassett’s two analyses 
and in the pair just recorded, the apparent percentage of copper has been raised, 
because the substance weighed really included the calcium phosphate and the traces 
of oxides of manganese and iron known to be present in turacin ash, and regarded as 
accidental or adventitious constituents thereof. This conclusion is strengthened by 
the following argument:—If turacin contains 8 per cent, of copper it must yield, when 
so incinerated that no loss occurs, quite 1 0 per cent, of CuO, which, added to the 1 per 
cent, of extraneous ash ascertained to be present, amounts to 11 per cent. But the 
true percentage of total ash is just under 10—a figure based on numerous determina¬ 
tions, and confirmed by a recent result of Professor Kinch, who, by oxidising '1522 
grm. of turacin with nitric acid, evaporating the solution to dryness and incinerating 
the residue, obtained '0149 grm. of total ash, equal to 9'79 per cent. If, then, turacin 
be a definite compound possessing but one essential metallic constituent, there cannot 
be more than about 7 per cent, of copper in it. It might perhaps be argued that the 
iron and manganese are not accidental impurities, and that turacin may, after all, 
contain 8 per cent, of metal, namely, about 7 parts of copper and 1 part of iron and 
manganese. This assumption is, however, untenable, for the oxides of iron and 
manganese found in the ash of all preparations of turacin constitute but a small 
part of the 1 per cent, of so-called accidental ash, and are accompanied by other 
bodies such as calcium phosphate. I conclude, therefore, that the volumetric deter¬ 
minations of copper are to be accepted in preference, and that the higher figures 
obtained by precipitation w.th sodium hydrate arose from the presence of impurities. 
