OTHER MINERAL SUBSTANCES USED AGAINST THE WORMS. 153 
All that baa been said under the head of Paris green as to the desir- 
ability of adding a small quantity of Hour or other substance to give 
adhesiveness to the liquid will hold equally true of London purple. 
This method is very cheap; labor and machine constituting by for the 
greatest part of the expense, while the cost of the poison per acre does 
not exceed 3 cents. 
OTHER MINERAL SVBSTJXCES. 
SALT AND SALTPETRE. 
We have heard common salt frequently recommended as a remedy for 
injurious insects, and it unquestionably possesses insecticide properties, 
especially when dissolved in water, affecting and killiug the insect upon 
contact. Unfortunately, however, its effects on the plants aie much 
more marked, and we have thus the same obstacles to its application 
as with kerosene and Other oils. Moreover, salt is decidedly interior to 
kerosene as an insect icide. but scarcely less injurious to tin 1 plant ; hence 
in the case of salt it is much more difficult to find the u right proportion" 
in which it could effectually he applied ; in other words, that proportion 
of salt which is not injurious to the plant will be much too weak to seri- 
ously affect the worms. 
Nevertheless, in view of the constantly recurring recommendations of 
salt as remedy for the Cotton Wonns in the papers, we had some ex- 
periments made in the lield by Professor Stelle ami Mr. Schwarx. The 
former gives the following report in his diary: 
Septcmbir'St, lfiSU. — Sprinkled two row* of cotton across a .square acre with a solution 
made of salt pel re in proportion of 1 ounce to the gallon of water ; also two rows with 
a solut Ion of common salt, A ounces to the gallon of waier. 
September 28. — Can see an effect favorable on all the rows of cotton sprayed yeeter* 
day, though the worms ha\e not entirely disappeared fmm any. 
September 29. — Looking over my work on Monday, I tind considerably less worms on 
the saltpetre rows than when' nothing has been used, and very few indeed where the 
common salt was applied. The salt has slightly curled some of the leave*. Sprinkled 
two row s carefully wit h common sait in proportion of 2 ounces to the gallon of water. 
Septembtr ;>0. — The rows sprinkled with salt yesterday have shown no satisfactory 
result. 
This report would seem to give a satisfactory result as to the applica- 
tion of salpeter, but uo farther experiments have beeo made so Car. 
Much less favorable is the following report by Mr. Schwarz on an 
experiment made with common salt: 
August *J(>. — 1 applied common salt in the proportion recommended to me, viz., at the 
rate of 1 gallon of salt to 40 gallons of water. The salt was thoroughly dissolved in 
the water and the liquid applied by means of the fountain pump, wetting the leaves 
on some plants pretty thoroughly. Upon examination, 16 hours afterwards, a small 
number of dead worms (not 10 per cent, of the whole number), mostly young ones, were 
found, the leaves being somewhat shriveled up even where not exposed to the sun; but 
wherever the solution was applied thickly the leaves had assumed a peculiar pale 
green color and were quite stilf. The worms did not feed upon such leaves, which, on 
the second day. proved to be killed. 
August 28. — Applied the solution at the rate of 1 gallon of salt to bO gallons of water. 
No effect upon worms observed the next day or afterwards. 
