384 CUTANEOUS SECRETIONS. 



The smegma prceputii of the horse, which I obtained for 

 analysis, was of a blackish grey colour,, soft and plastic like wax, 

 and somewhat viscid when fresh; but when dried, it was hard, 

 almost brittle, and presented a glistening fracture. 



Little remains to be noticed regarding the different methods of 

 analysing these secretions, both qualitatively and quantitatively, in 

 addition to the ordinary general rules, and to the special remarks 

 on the detection of each individual constituent. 



The above mentioned albuminous substance can be only approxi- 

 mately determined, since it can only be extracted by acetic acid 

 from the residue of the matter that is left after extraction with 

 ether, alcohol, and water; this acid, however, abstracts a little 

 albuminous matter and a certain quantity of earthy salts from the 

 cellular structures of the residue. I determined this matter in the 

 following manner : I dried the residue after its extraction with 

 indifferent menstrua, and determined its weight ; I then digested 

 it for several hours in moderately dilute acetic acid, rinsed it, and 

 after drying again, weighed it ; the loss of weight indicated the 

 sum of the matters extracted by the acetic acid ; the acid solution 

 was evaporated, and its residue, without any further treatment, 

 was incinerated for the determination of the mineral matters ; the 

 weight of the ash was then deducted from the loss of weight which 

 the residue had saifered from the acetic acid. I thus obtained the 

 number representing the quantity of the albuminous substance 

 contained in the secretion. 



With regard to the carbolic acid, we have only further to add, 

 that its presence is by no means so easily to be recognised as 

 might be supposed from the above named reactions; for, inde- 

 pendently of the extremely minute quantity in which it occurs in 

 castoreum, the application of pine or fir shavings, saturated with 

 hydrochloric acid, is exposed to certain fallacies ; for the shavings 

 of these woods, after being acted on by this acid, readily assume a 

 bluish green colour on exposure to the sun : hence it is necessary, 

 before applying this test, to separate the carbolic acid as completely 

 as possible from the resinous and fatty constituents of the casto- 

 reum, which, however, in consequence of the slight solubility of 

 carbolic acid in alcohol and ether, and its high boiling point, 

 187 C, is altogether impracticable when only small quantities are 

 present. 



We have nothing to add to the observations contained in the 

 first volume, regarding the method of detecting and separating the 

 lipoids and fats, hippuric, benzoic, and uric acids, oxalateoflime, &c. 



