CANTHARIDIN. 157 



strongly it is volatilized in a white smoke, which condenses into 

 a white crystalline sublimate. The smallest particle of this mat- 

 ter is sufficient to raise a blister on the skin. Even the eyes, the 

 nose, and the organs of respiration cannot be exposed to the va- 

 pour of it without hazard. 



Cantharidin is neutral, neither reacting as an acid or base. 

 It is insoluble in water, almost insoluble in cold alcohol, but so- 

 luble in that liquid when boiling-hot. It is very soluble in ether 

 and in the fat oils. It was analyzed by M. Regnault ;* 1060 

 parts gave 2293 of carbonic acid, and 576 of water. Hence the 

 constituents are 



Carbon, 59.00 



Hydrogen, 6-04 



Oxygen, 34-96 



100-00 



He represents the constitution of cantharidin by the formula 

 C 10 H 6 O 4 . If we calculate from this, we get 



10 atoms carbon 7-5 or per cent, of 61-21 

 6 atoms hydrogen = 0-75 ... 6-13 



4 atoms oxygen = 4- ... 32'66 



12-25 100 



There is always a deficiency of carbon in the ordinary analyses 

 by Liebig's apparatus. This occasions a corresponding increase 

 in the oxygen. 



CLASS IV. 



OF ANIMAL COLOURING MATTERS. 



THESE have hitherto been very imperfectly investigated. On- 

 ly a very few of the great number of colouring matters which 

 occur in 'the animal kingdom can be noticed here ; because they 

 have not hitherto attracted the attention of chemists. 



* Ann der Pharm. xxix. 314. 



