148 
heating pure phenol with oxalic and sulphuric acids for a 
few days to about 105°C. Although a good product is thus 
obtained, the yield is but small, while on heating the mix- 
ture longer or to a higher temperature bye-products are 
formed. Some chemists have stated that the formation of 
the latter cannot be avoided, and that it is very difficult to 
obtain thus a pure aurin. We believe that we are able to 
explain these different results; the formation of a pure 
compound depends much on the proportions and the manner 
in which phenol and the acids are mixed. As however the 
preparation of pure aurin by this method is a very tedious 
process, we endeavoured to obtain it from the commercial 
product by the method which we have described in our first 
paper and purifying it by repeated recrystallisation from 
alcohol, the crystals separating out first being used for 
further purification, because we found that the purer aurin 
is, the less soluble it becomes, its solubility being increased 
by the admixtures which are present in the crude product. 
Another method for purification which we employed con- 
sisted in washing good commercial aurin with cold alcohol 
until only a comparatively small residue was left, which was 
then further treated as above stated. 
The different crops of crystals were analysed, and the 
purification continued until the product did not change its 
composition any more. A great number of analyses were 
thus required, and we have great pleasure in expressing our 
best thanks to Mr. L. T. O’Shea, who performed them with 
great care. 
The results did not, however, agree with our former; the 
product having a constant composition, and crystallising 
exceedingly well, gave numbers agreeing with the formula 
CjgH^Oo, We therefore again prepared aurin from pure 
phenol, and crystallised it repeatedly from alcohol, until its 
composition became constant, and found it to have the same 
formula. 
