126 EXPERIMENTAL FARMS 



5 GEORGE v., A. 1915 

 Analysis. 



Total solids at 100 degrees C, 26-58 grams per 100 c.c. containing 

 Mercuric chloi-ide, 261S grams per 100 c.c. 



This is a solution of mercuric chloride (corrosive sublimate), in an acid solu- 

 tion, the normality of which is .93. The colouring matter is evidently added as a 

 precautionary measure, corrosive sublimate being an active aud virulent poison tu 

 man and beast. 



VKLVAS LAWN SANDWEEl) KII.LEH AND FF.imLiZER. 



Lahorafori/ No. 15045. — Submitted by Horticultural Division; forwarded for 

 trial by Robinson Bros., Ltd. It is in the form of a powder, of grayish-white 



appearance. 



Analysis. 



Per Cent. 



Suipl'.ate of iron 11.40 



Sulphate of ammonia' 26.60 



^Mineral matter insoluble in acid, sand, etc 60-.30 



' Equivalent to nitrogen 5.6 



Fi-ee from arsetiic. 



\ 



This is a mixture of sulphate of iron and sulphate of ammonia with about 60 per 

 cent of sand. Sulphate of iron is used for the destruction of dandelions in lawns, but 

 with somewhat doubtful success. Sulphate of ammonia is valuable as a fertilizer 

 for supplying available nitrogen. 



TOB.VOCO DECOCTION. 



Laboratory No. iC566.— Submitted by the Division of Entomology, as a decoc- 

 tion made in the course of experimental work for the destruction of aphides. The 

 decoction was made by boiling one pound of tobacco ' stem butts ' in two gallons of 

 water, allowing the preparation to simmer for one hour. Water from time to 

 time was added to replace that lost by evaporation. It was of the colour of fairly 



strong tea. 



Analysis. 



Nicotine 45 per cent. 



The following report was written on this sample : ' We can find but little 

 evidence in such literature as we have access to, as to the " strength " of the tobacco 

 decoction necessary to be effective in the destruction cf aphides, that is, interpreting 

 strength as percentage of nicotine present. It has always seemed probable that the 

 insecticidal value of the decoction might depctid in some measure on other com- 

 pounds present — tannin, bitter principles, etc. The nicotine present in tobacco 

 stems is stated to be about 0-5 per cent and the directions for making the decoction 

 l.^ually call for 1 to 2 lbs. to 2 galbus (20 lbs.) of water, the water while still boil- 

 ing being poured over the stems and the mass allowed to steep overnight. Whether this 

 extracts all the nicotine we have no evidence. 



' The Kentucky Experiment Station reports on a tobacco extract prepared in St. 

 Louis, U.S.A. (evidently by concentration) that contains 3-0 per cent nicotine, 

 stating that the experiments showed that this extract diluted in the proportion of 

 1 part to 70 parts of water, was eifective as a spray for aphides. If we assume 

 that the nicotine present measures the insecticidal value of the spray, then the 

 decoction under discussion would bear considerable dilution, say 1 part to 10 parts 

 water. There is, liowever, considerable doubt as to such diluted decoction being 

 effective. Careful experimental work is evidently needed, with the analysis of such 

 sprays as may be found effective.' 



