86 
CATTLE DISEASES IN AFRICA. 
dermatodectes. They describe the customs, the mode of repro- 
duction, the instincts of these various kinds of animalcules. 
In a second paper, they will speak of contagion from animals 
to man. — Medical Times and Gazette , 
SOURCE OE ERROR IN MARSH’S TEST FOR ARSENIC. 
Some time ago M. Blondlot, of Nancy, who is both an 
able physiologist and a chemist, sent a paper to the Academic 
de Medecine, on a source of error in making use of Marsh’s 
method for finding arsenic. A report by M. Poggiale on 
this paper was read at the Academy on Tuesday last. It is 
known that Messrs. Flandin and Danger have proposed to 
modify the method of Marsh by applying sulphuric acid to 
carbonize the organic matters suspected of containing 
arsenic. M. Blondlot, while examining the stomachs of 
three persons who had been poisoned by arsenious acid, 
found on the mucous membrane small fragments of this 
acid, which superficially were of a fine yellow colour. He 
thought that this yellow matter resulted from the formation 
of a sulphide of arsenic, resulting from the action of sul- 
phydric acid on the arsenious acid, and ulterior experiments 
proved the correctness of this view. As sulphydric acid is 
formed in putrefied organic matters, if they contain arsenic, 
the sulphide of arsenic will be formed ; and M. Blondlot 
shows that employing sulphuric acid to carbonize these 
matters, will leave with the carbonized parts the sulphide of 
arsenic, so that a portion of the poison will be lost. The 
committee of the Academy has ascertained the exactitude of 
the assertions of M. Blondlot, and to avoid this source of 
error they propose to throw upon the carbonized remnant a 
great deal of concentrated and boiling nitric acid, so as to 
transform the sulphide of arsenic into arsenious acid. By 
distilled water the excess of nitric acid is then expelled, and 
the arsenic may easily be found by the method of Marsh.— 
Medical Times and Gazette . 
CATTLE DISEASES IN AFRICA. 
The disease ( peripneumonia ) passing under the term horse- 
sickness is an insurmountable obstacle to the introduction of 
