35 
taken immediately from the barrels at almost a boiling temperature 
and sprayed at once on the trees. A series of experiments was also 
made with the preparation of this wash on a smaller scale, following 
practically the same formula. The products obtained were submitted to 
the Chemist of this Department for analysis, and the assistant chemist 
charged with the work was especially advised just what features were 
supposed to be desirable and what points the analysis should bring out. 
The result of this analysis, made by Mr. J. K. Haywood, of the 
Bureau of Chemistry, as reported by Dr. H. W. Wiley, Chief Chemist, 
is given ina footnote.’ It is very interesting and valuable as showing 
the probable exact chemical nature of the wash in a dry climate and 
correspondingly also in a wet climate, in these respects practically sub- 
stantiating the theory which the writer had announced several years 
ago. The practical application of this wash, as described above, was 
made to pear and plum trees, both infested with the San Jose scale, 
the plum trees being very thickly covered with the scale from top to 
bottom and the pear trees scaly from the butts upward three or four 
feet, scattering more or less over the whole tree. The plum trees had 
also more or less of Diéaspis pentagonda. 
The question naturally arose, in view of the extreme heat at which 
the liquid was applied, whether any results gained might not be due 
to the high temperature of the liquid rather than from any insecti- 
cidal action. To test this matter some plum and peach trees covered 
with Diaspis pentagona were sprayed on March 27 with water at 
stances in solution: A large amount of (CaS) calcium sulphid, some of the higher 
sulphids of Ca (as CaS, and CaS;), small amounts of (CaSO,) calcium sulphate, and 
traces of (CaSO,) calcium sulphite, and a large amount of (CaS,O,) calcium thio- 
sulphate; also some of the excess of Ca(OH), lime is in solution. The residue is 
composed of lime. 
On eyaporating down a portion of the wash, with blast and at a gentle heat, no 
decided change takes place. Calcium sulphid still remains, as does calcium thio- 
sulphate. A small amount of sulphur is deposited (doubtless from the polysulphids 
of calcium), and the amount of calcium sulphate is increased to a small degree. 
If such a wash were applied to trees in a dry climate, the various compounds formed 
would remain for a long time and only gradually decompose. Eventually, however, 
the calcium sulphid would decompose, most likely forming calcium sulphate and some 
hydrogen sulphid (H,S), and the calcium thiosulphate would decompose, first setting 
free sulphur and calcium sulphite, which last would oxidize to calcium sulphate. 
The lime would change to calcium carbonate (CaCO,) and the polysulphid would 
break down, yielding sulphur and calcium sulphid, which would in turn change as 
above. 
In a wet climate the calcium sulphid and the calcium thiosulphate would soon 
leach out, leaving behind small amounts of calcium sulphate and a large amount of 
lime, which would in turn form insoluble calcium carbonate. In this latter case the 
tree would still remain white and appear to still have the wash upon it, but, in fact, 
very little other than the calcium carbonate would be left. 
