96 
Proceedings of the Royal Society of Edinburgh. [Sess. 
VII. — Preliminary Note on the Action of Nitric Anhydride on 
Mucic Acid. By Professor A. Crum Brown, F.R.S. and G. E. 
Gibson, B.Sc. 
(MS. received October 12, 1908. Read July 21, 1908.) 
In the course of his researches on mucic acid, Professor Crum Brown found 
that this acid could not readily be nitrated in the ordinary way. 
Mucic acid dissolves, to a certain extent, in a mixture of concentrated 
sulphuric and nitric acids, but on standing separates out again apparently 
unchanged. An exceedingly small quantity of a crystalline nitrate can, 
however, be obtained by pouring this mixture into a large volume of acid 
water and immediately shaking up with ether. On evaporating the 
ethereal layer the nitrate is obtained, but the yield is so small that this 
method of preparation is not practicable. 
With nitric anhydride, however, a good yield of a crystalline nitrate is 
obtained. 
The method is the same as that described in a previous paper for the 
preparation of tartaric acid dinitrate. Not more than 20 grams of mucic 
acid should be treated in one operation, and both the mucic acid and the 
nitric anhydride should be cooled in ice before mixing. 
If these precautions are not taken, considerable decomposition of the 
nitrate may take place. 
In one experiment, 16 ’3 grams of Merck’s pure mucic acid were mixed 
with about 50 grams of nitric anhydride. The mixture was left over- 
night in an evacuated desiccator containing solid caustic soda. It was then 
treated with ether in a Soxhlet tube, the filter of which had previously been 
weighed. The ethereal extract was evaporated at the ordinary temperature 
with the help of a steam -jacketed “ Geryk ” vacuum pump. 
Twenty-five grams of the nitrate were obtained, and 0'5 gram of 
unchanged mucic acid remained on the filter. If no mucic acid had been 
lost in the process of preparation, these figures would correspond to the 
formation of the trinitrate. 
There is, however, always some loss caused by decomposition of the 
nitrate, so that there can be little doubt that the substance which is obtained 
is the tetranitrate of mucic acid. 
Many different preparations were analysed, both by Walter Crum’s 
mercury method and by combustion in vacuo, and the results of these 
