119 
ARSENITE OF SODA AND FOWLER ; S SOLUTION OF ARSENIC. 
These have also been used for the destruction of insects, but have 
been discarded probably on account of their cost and injurious effects 
upon foliage. 
ARSENIURETTED HYDROGEN GAS.* 
This gas has been used with success by D. W. Coquillett in Cali- 
fornia for the destruction of scale-insects affecting the Orange. 
ARSENICAL MIXTURES. 
Within a few years past it has been found advantageous to apply 
the arsenites along with other substances, and chiefly for three reasons : 
(1) to economize time where an arsenite and a fungicide are needed upon 
a plant at the same time; (2) to prevent the injuries that the arsenites 
usually do to foliage; (3) to increase the effectiveness of the j)oison by 
using with it some sticky material as flour, paste, or molasses to make 
it adhere longer and in larger amount upon the leaves. 
Who first conceived the idea of combining the arsenites with fungi- 
cides it would be impossible to say. The earliest mention we have been 
able to find of anyone having used an arsenite with a fungicide for the 
purpose of destroying both insects and fungi is by Mr. 0. M. Weed, 
in Bulletin 7, vol. n, of the Ohio Experiment Station (September, 
1889). The application was reported to have destroyed Potato-beetles 
and lessened the attack of the blight. 
Now such mixtures are commonly recommended, but some of the 
fungicides, on account of their solvent action upon the arsenites, 
cannot be safely used with the latter upon plants. 
t It has been proved by experiments that London purple, Paris green, 
and white arsenic when applied upon foliage alon g with Bordeaux mixture 
do less injury than when applied in water alone; tthat London purple 
and Paris green are not more injurious to foliage when applied in 
| resin mixture; that foliage will suffer greater injury when arsenites 
are used in § sulphate of copper solution, strong soapy mixture, |Eau 
celeste or ||iron chloride solution. 
Whether the arsenites may be used with ammonia carbonate of cop- 
per or not there seems to be a difference of opinion and experiments 
are needed to decide the matter. One important question then that 
should always be decided before recommending the mixture of any 
substance with an arsenite to be applied to plants is, how will the sub- 
stance added affect the solubility of the arsenite. fl If it renders it 
* Rep. of Ent., Dept. of Agr., 1888, p. 127. 
tBul. 10, Iowa Exp. Sta., p. 417; Bui. 4, vol. Ill, 2d Series, Office Exp. Sta., p. 
143; Bui. 48, Cornell Exp. Sta., p. 274; Bui. 77&, N. C. Exp. Sta., p. 5. 
$ Bui. 10, Iowa Exp. Sta., p. 415. 
§ Bui. 10, Iowa Exp. Sta., p. 418. 
|| Bui. 776, N. C. Exp. Sta., p. 8. 
IT Bui. 77&, N. C. Exp. Sta., p. 10. 
9052— ]No. 2 5 
