503 
from 68°-acid nuclei by boiling with water. The solution was evapo- 
rated down until the acid separated out as an oil at ordinary 
temperature. This solution gives crystals of 42°-acid on cooling to 
O°. The presence of a small quantity of liquid acid indicates at 
once the occurrence of undesired inoculation. 
Small quantities of this solution were introduced into the flasks 
with the cotton wool plugs. 
After filling and drawing air through the flask, the solution was 
again boiled. After cooling the flasks were placed in a freezing 
mixture. The temperature of the mixture was in some experiments 
about —10°, in others about —16°. After twenty-four hours these tem- 
peratures were 0° and 5° respectively. (The mixtures were kept in 
a box packed with hay). 
The cooling was continued until transformation had taken place. 
This point is easily recognised from the more copious crystallisation 
and also from the form of the crystals. After the ice had melted, 
the flask was opened, the tube with the plug withdrawn, and the 
solution carefully poured out so that the crystals as far as possible 
remained in the flask. The flask was then closed in the usual way, 
and the few drops of water were removed by means of a stream 
of dry air at the ordinary temperature. The melting point was then 
determined. 
It was found that, whenever the initial temperature of the 
mixture was —10°, the 58°-acid was always formed, while, when 
the initial temperature was —16°, the 58°-acid was formed in 
nearly as many cases as the 68°-acid. (58°-acid in five experiments 
and 68°-acid in seven). There is apparently a range of temperature 
within which the 58°-acid is formed, while at lower temperatures 
the 68°-acid is obtained. 
The transformation at —10° sometimes requires several days; 
at —16° it is complete after a few hours. In this way a method 
is given by which one or other of these acid forms may be prepared. 
Experiments with a solution in petroleum ether of low boiling-point 
were carried out as follows. A dilute solution of the 68°-acid in 
petroleum ether was prepared and freed from nuclei at the ordinary 
temperature. Portions of this solution were introduced into several 
flasks through which a rapid stream of air was drawn. After the 
cotton-wool plug had been pushed below the side tube, a large 
portion of the solvent was distilled off. The solution was then cooled. 
It was found that, both when the initial temperature was —10° and 
when it was —16°, the 58°-acid was obtained in several cases, but 
’ 
generally the 68°-acid was formed. 
