The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1877-02-07
THE FARM AND HOUSEHOLD.

Ausect FOIsOns IN agriculture.
The following paper was read before the
Public Health Association, at Baltimore, by r.
G. Kedzie:
SIN his contest with insect foes, the farmer
often finds p0isons the most ready means of
defence, but great care should be exercised in
the use OF such agents Not only the immedi-
ate benefits, but also the remote and contingent
consequences demand attention. A safe Insect
poison should combine the following properties:
LIST. 1t should, in small quantity, effectualy
destroy the insect; 3D. 1t should be easy to APP
ply; Sd. 1t must not injure the crop in any
way or endanger the health of the consumer of
the crop; 4th 1t must not injure any succeed
ing crop; 9Th. 1t must not injure the health of
the person who applies it; 9th. 1t should be
in use on the farm and in the household
No substance has vet been found which
combines all these qualities Mr..
KedZie's paper was confined to the con-
sideration of tie arsenical poisons, viz; "whte
arsenic, arsenate of soda and Paris green, and
after pointing out the dangers from their use
and the influence of arsenic on plant-ife, cit
ing the experiments of Prof Edmund Davy,
and counter experiments of Ogston, of Daube-
ny and Brodie, also the experiments of Me-
Murtrie, of the Department of Agriculture, he
considered the questions: Will Paris green
poison plants? Will it reappear in those parts
of plants used for food? Used in large quanti-
ty it may kill the potato vines, but does not
reappear in the potato tuber. Such potatoes
have been used for years in large quantities,
but no case is known of poisoning by their USE
Direct inquiries made by the Michigan State
Board of Health resulted in answers from
more than 1000 clerks of local boards of health.
and in 1873 only five clerks reported cases of
poisoning by the use of Paris green. By fur
Their examination it was found that in the cas-
es reported no Que was poisoned by eating the
potato, but only by careless handling Of the
Paris green. When Paris green is applied to
wheat during its period of growth, or is present
in the soil on which wheat is grown from hav-
ing been applied to previous crop, the arsenic
did not appear in the grain, and thus injure or
destroy its value as food, nor was it found in
the straw. Experiments with cabbage raised
on soil dressed last year with Paris green to
cabbage. To the questions, What becomes of
Paris green in the soil? Why does it not re-
appear in vegetables, nor poison our wells and
fountains? The reply that it is insoluble in
pure water is not enough, for it is sensibly
soluble in the natural agricultural solvents
The paper, in discussing these questions, cites
many experiments to show the action Of the
soil on chemical substances, and particularly
GU Paris green, which established that Paris
green, after three months contact with the
soil. does not exist as aceto-arsenite of copper;
that the material had not washed out of the
soil, and that the arsenic comported itself, so
far as solubility is concerned, as it would If 1t
existed in the form of basic arsenite of iron.
The c0nclSl0nS drawn are that Paris green be-
ing deadly poison should be hs ndled with ex-
treme care, as inhalation of the dust by contact
of the material with sores and raw surfaces,
and even by contact with moist and perspiring
surfaces, it may produce dangerous effects
that while classed as an isoIuble substance.
Paris green becomes soluble to sensible degree
by the action OF what may be called the natural
agricultural solvents, of which carbonic acid
and the solvent action of the minute roots of
plants may be regarded as the most active: that
solutions of arseniOus acid and of arseuites tend
to pass into an insoluble condition in the soil,
in which arsenic is insoluble by the natural ag.
ricultural solvents; that while other agents may
assist in fixing arseniouS acid in the soil, the
hydrated oxide of iron is probably the most
potent factor in producing this insoluble condi-
ton; that enough of this oxide is present in all
fertile soil to render inert comparatively large
amount of arsenic, and that it is to this agent
that we probably owe our safety when Paris
green is applied to the soil. When Paris green
is applied to the soil in such quantity that the
hydrated oxide of iron present in such soil is
not sufficient to speedily change it to the inert
condition, we should expect this agent to injure
the health or even destroy the life of the plant.
The limit of saftey would naturally vary with
varying compositions of soils. Mr.. McMurtrie
places the limit in one instance at 900 pounds
to the acre, quantity vastly in excess of any
requirements as an insect poison. Finally,
the power of the soil to remove from solution
and hold in an insouble form arsenious acids
and arsenites, will protect the water supply
from deadly contamination by this agent, unless
the poison is used in excess of any REQUIRE
meDtS az an insect DESTROYER