——> eS 
~ 1905] LRUE & OGLEVEE—TOXIC ACTION OF POTSONS 2 
ment with distilled water. It was noted that gas bubbles were repeat- 
edly found over the surface of the submerged particles of coal and 
that after being removed by thorough stirring these would again 
form. This evolution of gas continued during the entire time in 
which the coal was under observation. The nature of the gas was 
not determined. 
Finely divided pure paraffin of high melting point was also made 
use of. Investigations made on the effect of paraffin on the electrical 
conductivity of pure water have shown that paraffin does not notice- 
ably increase the conductivity and seems to be practically insoluble 
in water.” 
Owing to the lightness of the paraffin, the finely divided particles 
floated on the surface of the solutions, but owing to the small spaces 
between the pieces, the solution rose by capillary action among them 
and they became, in effect, submerged in the solutions. 
At the suggestion of Dr. HENRY KRAEMER, of the Philadelphia 
College of Pharmacy, unruptured potato starch grains were tried. 
A stock was freshly prepared from potatoes by crushing and washing 
out the starch grains, care being taken to avoid other structures from 
the tuber. The starch thus obtained was dazzlingly white and dis- 
tilled water in which a portion of the material was allowed to stand 
for some time gave no starch reaction when treated with iodine. 
By rubbing up a little of the same starch with a little distilled water 
a strong starch reaction appeared on adding iodine solution. Careful 
washing removed all traces of other substances. 
The toxic substances receiving most attention in this investiga- 
tion were those which have been shown to possess great poisonous 
activity. Copper sulfate, silver nitrate, mercuric chlorid, hydro- 
chloric acid, sodium hydroxid, thymol, and resorcinol may be 
especially mentioned. The chemicals in the case of the heavy 
metals were Merck’s guaranteed reagent grade. The remaining 
compounds were recognized makes of chemically pure’ quality. 
_ The solutions were made up with such care as the apparatus of the 
2 We are informed that investigations by F. K. CamMERon and Lyman J. Briccs 
of the Bureau of Soils, U. S. Department of Agriculture, show that high grade paraffin 
of high melting point, of the sort here used, has but a minimal effect on the electrical 
conductivity of distilled water in which it is placed. 
