G60 ARSENIC IN ARTIFICIAL MANURES. 
and that every portion of them appeared to have imbibed the 
poison. 
This experiment having shown me that arsenic might be 
taken up in considerable quantity by plants without its de¬ 
stroying their vitality, or appearing even to interfere with 
their proper functions, I proceeded to ascertain if the arsenic 
as it existed in different artificial manures (such as the super¬ 
phosphate), would in like manner be taken up by plants grow¬ 
ing where those in manures had been applied. To determine 
this, I transplanted, last April, a small cabbage-plant into a 
flower-pot which I had previously put a mixture of one part 
of superphosphate to four parts of garden mould. The cabbage 
after a short time appeared to recover the transplanting, and 
when it had been growing in the mixture for three weeks, I cut 
off the top of the plant, which looked perfectly green and 
healthy. On examining it for arsenic, I obtained the most dis¬ 
tinct indications of the presence of that substance, though only 
a very small amount of cabbage, viz., 113 grains, were used in 
the experiment. This result was therefore perfectly conclusive 
as to the power possessed by some plants, at least, of taking 
up arsenic from manures containing that substance. As in 
this experiment I was aware that I had placed the plant in 
a most favourable condition for absorbing the poison, and 
that a larger proportion of superphosphate had been employed 
than was used in practice, my last experiments were to 
ascertain if the presence of arsenic could be detected in our 
crops grown with superphosphate in the ordinary way. 
I procured for this purpose some Swedish turnips which 
had been grown with superphosphate, and having most care¬ 
fully washed each turnip to remove every particle of adhering 
clay, I cut up in small pieces 2lbs. weight of one of the 
turnips, and boiled them in a large glass flask for about three 
hours with 36 fluid ounces of distilled water, to which I had 
added 3 ounces of hydrochloric acid (spec. grav. 1.14), placing 
in the mixture 100 grains of perfectly clean and bright 
turnings of metallic copper. After removing the copper 
turnings and washing them well with water to seperate the 
vegetable matter, and then boiling them for a few moments 
in a mixture of spirit and ether, to remove any fatty matter 
which might have been deposited on the metallic copper, and 
finally, after the spirit and ether had been poured off, washing 
well with distilled water, the copper was found to have ac¬ 
quired the characteristic steel-grey appearance produced by 
the presence of arsenic under such circumstances. 
The copper turnings were then carefully dried, and after¬ 
wards heated strongly in a glass tube closed at one end, when 
