4 
note.! It is very interesting and valuable as showing the probable exact chem- 
ical nature of the wash in a dry climate and correspondingly also in a wet clim- 
ate, in these respects practically substantiating 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, scat- 
tered more or less over the whole tree. The plum trees had also more or less of 
Diaspis pentagona. 
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 tempera- 
ture of the liquid rather than from any insecticidal action. To test this matter 
some plum and peach trees covered with Diaspis pentagona were sprayed on 
March 27 with water at boiling temperature, or nearly so, the nozzle being held 
within 3 or 4 inches of the bark and the spraying being very thoroughiy done. 
At a distance of 18 inches, as tested by spraying one’s hand, the mist or spray 
was barely warm; ata distance of 12 inches, fairly hot; and very hot from 4 
to 6 inches. The bark of the trees sprayed was cold to the hand as soon as 
spraying stopped. This hot-water spray, brought to bear closely on the scale 
insects, it was thought would kill them, although it would of course be imprac- 
ticable to make such close-range application in general practice. On the 
contrary, however, the scales remained in a vigorous, healthy condition, and 
apparently did not suffer in the least from the warm douche. 
The results, therefore, gained by the lime, sulphur, and salt wash may be 
properly ascribed, it is believed, to a true insecticidal value of the substance 
rather than to the temperature of the application. The trees treated with this 
wash remained nearly snow-white, little, if any, of the mixture being taken off 
by the light snow and rain of the 25th and 26th instant. Discoloration of the 
Diaspis began to be noticed on the 27th instant. On April 18 the Diaspis scale 
insects killed ranged between 20 and 50 per cent on the young, vigorous limbs. 
All were dead on the old trunk, where the wood was in a very unhealthy con- 
dition owing to the completeness of the infestation, both by the Diaspis and the 
Aspidiotus. The San Jose scale, so far as investigation could determine, seemed 
1'The lime, salt, and sulphur wash, as finally prepared, contains the following 
substances in solution: A large amount of (CaS) calcium sulphid, some of the 
higher sulphids of Ca (as CaS3 and CaS;), small amounts of (CaSO,) calcium 
sulphate, and traces of (CaSO;) calcium sulphite, and a large amount of (CaS.QO3) 
calcium thiosulphate; also some of the excess of Ca (OH), lime is in solution. 
The residue is composed of lime. 
On evaporating 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 
thiosulphate. A small amount of sulphur is deposited (doubtless from the poly- 
sulphids 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. Event- 
ually, however, the calcium sulphid would decompose, most likely forming cal- 
cium sulphate and some hydrogen sulphid (H.2S), 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 polysulphids 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. 
