( 110 ) 



In the other, the diformin, was treated daily, during a month, 

 with a large quantitj of anhydrous oxalic acid, but even then the 

 result was not more favourable. 



The difficulty in preparing large quantities of perfectly anhydrous 

 oxalic acid coupled with the fact that carbon monoxide is formed 

 in the "reaction, which necessitates a formation of water from the 

 formic acid, satisfactorily explains the fact that the reaction does not 

 proceed in the manner desired. A complete separation of di- and triformin 

 cannot be effected in vacuo as the boiling points of the two compounds 

 differ but little. 



I, therefore, had recourse to the action of anhydrous formic acid 

 on diformin. 1 prepared the anhydrous acid by distilling the strong 

 acid- with sulphuric acid in vacuo and subsequent treatment with 

 anhydrous copper sulphate. Even now I did not succeed in preparing 

 the triformin in a perfectly pure condition, for on titration it always 

 gave values indicating the presence of some 107o of diformin. 



Afterwards, when 1007o formic acid had become a cheap com- 

 mercial product, I repeated these experiments on the larger scale, 

 but, although the percentage of diformin decreased, a pure triformin 

 was not obtained. 



I had also tried repeatedly to obtain a crystallised product by 

 refrigeration but in vain until at last, by cooling a formin with 

 high formic acid content in liqueiied ammonia for a long time, I 

 was fortunate enough to notice a small crystal being formed in 

 the very viscous mass. By allowing the temperature to rise gradually 

 and stirring all the while with a glass rod, I succeeded in almost 

 completely solidifying the contents of the tube. If now the crystals 

 are drained at 0^ and pressed at low temperature between filter 

 paper and if the said process is then repeated a few times, we 

 obtain^ finally, a perfectly colourless product melting at 18°, which on 

 being titrated gave the amount of formic acid required by triformin. 



The sp. gr. of the fused product at 18° is 1.320. 



/if, = 1.4412. 



lo 



MR. 35.22 ; calculated 35.32. 



The pure product when once fused, solidifies on cooling with great 

 difficulty unless it is inoculated with a trace of the crystallised 

 substance. On rapid crystallisation needles are obtained, on slow 

 crystallisation large compact crystals are formed. 



In vacuo it may be distilled unaltered; the boiling point is 163° at 

 38"^'". On distillation at the ordinary pressure it is but very slightly 

 decomposed. The boiling point is then 266°. A product contaminated 



