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EDITORIAL OBSERVATIONS, 
percha sides and a parchment-paper bottom. The mixed 
liquid that is to be analysed is put into the dialyser, and the 
dialyser is floated in distilled water contained in a flat basin. 
At the end of twenty-four hours, the crystallisable sub¬ 
stances contained in the mixed liquid will have become 
diffused in the distilled water of the basin, leaving the 
gelatinous substances of the mixture still in the dialyser. 
Ity means of this dialysing apparatus, arsenious acid, 
metallic salts, strychnine, and other poisons, mineral and 
organic, can be readily separated from organic solutions in 
medico-legal inquiries. The process has the advantage of 
introducing no metallic substance or chemical re-agent of 
any kind into the organic fluids. The arrangement for 
operating is also of the simplest nature. Yery minute 
quantities of arsenic have been separated by the dialytic 
process from egg albumen, gum arabic, isinglass, milk, 
porter, blood, and animal intestines, and obtained in a 
solution fit for the application of re-agents. 
The dialyser serves also for the separation and decom¬ 
position of many metallic salts; for the separation of urea 
and other crystallisable salts from urine; for the separation 
in general of all crystalloids or crystallisable bodies from all 
colloids or gelatinous bodies; and for the preparation and 
purification of such colloids as hydrated silicic acid, hydrated 
alumina, gelatine, albumen, starch, caramel, tannin, gummic 
acid, &c. In short, the dialyser is an instrument of great 
practical utility to all chemists, physiologists, &c., who are 
engaged in researches into the composition of organic or 
mixed liquids. 
Instructions for operating with the Dialyser .—The dialyser 
consists of two gutta percha hoops, one of them two inches 
deep, and the other, one inch deep. The two-inch hoop is 
slightly conical, and the one-inch hoop goes over the small 
end of the two-inch hoop. Both must be washed very clean 
with distilled water. The parchment paper that is to form 
the bottom must be about three inches wider than the small 
end of the two-inch hoop. 
Soak the parchment paper for about a minute in distilled 
water : stretch it evenlv over the small end of the two-inch 
