REPORT OF THE CHEMIST. 155 



the subsequent treatment being that already described in experiments A and B. The 

 filtrate from the magnesium hydrate was exposed in a shallow dish to the atmos- 

 phere of the laboratory for ten days. A considerable precipitation of carbonate of 

 lime ensued, due to carbonic acid in the air, and the water was no longer found to 

 be alkaline to test paper, proving the absence of caustic lime. 



From the results of these experiments, I think we may fairly conclude (1) that 

 by the use of lime-water the deleterious magnesium salt may be practically removed, 

 and. (2) that by the subsequent exposure of the treated water to the atmosphere, the 

 excess of lime used in precipitating the magnesia may be precipitated as the innocuous 

 carbonate. 



No practical application of this mode of treatment on a large scale has yet been 

 made, though its cheapness, simplicity and thoroughness warrant me in suggesting 

 it as well worthy of trial by those compelled to use water more or less impregnated 

 with Epsom salts. Wooden tubs or troughs could be used for the precipitation and 

 subsequent exposure, and no expense, save the cost of the burnt lime, need be 

 entailed. The ^precipitation of the magnesia and subsequently of the lime by ex- 

 posure might proceed simultaneously and in the same vessel, and the clear superna- 

 tant water subsequently poured or siphoned off. If such a pi'ocess were adopted, 

 care must be taken not to have too great an excess of lime, or the total conversion 

 into carbonate would take a very long time. 



It must be remembered that the water so obtained, though free from Epsom 

 salts and caustic lime, would not rank as first class. It would be a hard water, con- 

 taining both sulphate and bicarbonate of lime, the latter, however, could be got rid 

 of by a subsequent boiling, which would throw it down as the insoluble carbonate. 

 If the water, however, did not originally contain much sulphate and chloride of 

 sodium, I am of the opinion that a fairly palatable water would result, and certainly 

 one much more wholesome than the original. 



SLUG-SHOT: AN INSECTICIDE. 



A sample of this material was forwarded by a correspondent in Cape Breton, 

 accompanied by a request for its analysis and a report as to its value for killing the 

 potato beetle. 



It is a pinkish red, earthy powder, not unlike burnt clay. It was carefully exam- 

 ined for arsenic and other poisonous compounds with negative results. Further exami- 

 nation proved it to contain flowers of sulphur. This constituent was determined and 

 found to be 5'4 per cent. It is scarcely necessary to add that this material must prove 

 valueless for preserving potato vines from the ravages of the potato beetle. 



THE VALUE OF DILUTE SULPHUEIC ACID FOR CHECKING THE 



SPROUTING OF POTATOES. 



From a series of experiments recorded in my last report,* the conclusion arrived 

 at under the conditions of the experiments was that a 2 per cent solution of 

 sulphuric acid was valueless for checking the sprouting of potatoes. These trials 

 were, however, made in the spring, and the treated tubers were not protected from 

 light — conditions which it was thought were perhaps unfavourable to the best results 

 of the treatment. In the experiment the results of which are now given, the potatoes 

 were treated in the autumn and preserved in the dark. 



On November 30th, 1892, three varieties of potatoes, Early Ohio, Beauty of 

 Hebron and State of Maine were treated (a) for twenty minutes and (b) for one 

 hour with a 2 per cent solution of sulphuric acid. Immediately after the expira- 

 tion of these periods, the several samples were repeatedly washed with water, allowed 

 to drain, placed in jars and stored in a dark place, the other details of the experiments 

 being similar to those given last year. On March 13th, 1892, the potatoes were 



*Pages 141, 142, Report of Experimental Farm, 1S92. 



