412 
EDITORIAL OBSERVATIONS. 
hydrogen, and the heavy gas will at the same time pass up into the 
space occupied by the lighter gas.*’ 
Speaking of the practical application of dialysis ; he refers 
to it as being five-fold : 
“ 1. For the isolation of chemical substances in a state in which they 
have not hitherto been obtained by other means. 
“ 2. For the separation of the more active crystallisable constituents 
of vegetable substances from inert colloidal matter, and the production 
in this way of a new class of medicines containing the active principles 
of plants partially purified and in the state ofcombination in which 
they exist in nature. 
“ 3. For the separation of poisons, such as arsenic, emetic tartar, 
strychnine, morphine, &c\, from organic impurities, such as the contents 
of a stomach, without the employment of chemical agents. 
“4 . For the explanation of certain physiological and geological 
ph enomena. 
“5. For the elucidation of the normal condition, as to rest or motion, 
of the ultimate molecules of matter.” 
Of these we extract elucidations under the third and 
fourth heads, as more immediately bearing upon our division 
of science: 
“3. The third application of dialysis to be described, is for the sepa¬ 
ration of poisons from organic impurities in toxicological inquiries. It 
sometimes happens that it is very important in such inquiries to avoid 
the use of powerful chemical agents in preparing the suspected sub¬ 
stance for the application of tests. Thus, for instance, in testing for 
arsenic, acids and other chemical agents are usually employed, either 
to destroy organic matter that would interfere with the application of 
the tests, or otherwise to eliminate the poison ; and it is very difficult, 
if not impossible, to get these agents themselves perfectly free from 
arsenic. There may, therefore, be a suspicion that the arsenic was 
first put in with the chemical agents used, and then detected by the 
tests that are afterwards applied. This difficulty is perfectly obviated 
by resorting to dialysis. Arsenious acid and poisonous metallic salts, 
such as emetic tartar, may he separated from the organic impurities 
they would be mixed with in the contents of a stomach, or in other 
parts of the animal body, by means of dialysis, without using any 
other agent than distilled water, and the solutions thus obtained may 
he, sufficiently pure to admit at once of the application of certain tests. 
“We may also get out strychnine, morphine,and other organic poisons 
in the same way, for these substances all belong to the class of 
crystalloids which readily diffuse. I have myself obtained these sub¬ 
stances by dialysis from the stomach, the flesh, and the blood of 
animals that have been poisoned, distilled water alone being used for 
the extraction. 
“We thus have three valuable practical applications, of which this new 
process of dialysis is susceptible. But not only does it enable us to 
effect important changes in solutions with which we may desire to 
operate, it also admits of other applications. 
“4. Some of the results obtained in operating by dialysis, enable us 
to explain in a very satisfactory manner certain physiological and geo- 
