1921.] 



Insecticides and Fungicides. 



629 



Regarding c, lead arsenate paste consists primarily of mixtures of lead . 

 arsenates and water, some containing more water, others less. It is evident, 

 therefore, that if all makes of lead arsenic are diluted to the same extent the 

 resulting spray fluids may be either too weak or unnecessarily strong. The 

 purchaser clearly should know the " strength " of the paste he is buying, and 

 to this end it is laid down that the label on the container should state the 

 percentage of arsenic which the paste contains, and as this must be 

 stated in chemical terms which may not be clear to all, it must also be stated 

 what dilution is required to make up a standard spraying mixture containing 

 O'l per cent, of arsenic oxide. Such a mixture may be regarded as effective 

 under all conditions, although for use against young caterpillars it may be 

 unnecessarily strong. There is no difficulty, however, in diluting it to make a 

 f standard mixture. Thus in the case of a paste containing 20 per cent, of 

 arsenic oxide, the standard mixture consists of 1 lb. of paste to 20 gallons of 

 water, but f lb. to 20 gallons may be used early in the season against small 

 caterpillars. 



In any case a standard mixture may be obtained by adding 1 lb. of paste 

 to a number of gallons of water equal to the percentage of arsenic oxide — 1 lb. 

 to 20 gallons, with a paste containing 20 per cent., 1 lb. to 15 gallons with a 

 paste containing 15 per cent., and so on. 



In the case of d, when lead arsenate paste is purchased, the article should 

 obviously not consist of some other arsenate, as for instance calcium arsenate. 

 It is therefore laid down that apart from water, the total impurities in the paste 

 should not exceed 3 per cent. 



2. Lime-Sulphur (Solution of Sulphides of Calcium). — 



(a) Lime-sulphur solution as sold for agricultural and horti- 

 cultural purposes shall be made from lime, sulphur, and water 

 only. 



(h) The specific gravity of the solution as sold shall not be 

 less than 1.3 at 15° C. 



(c) The solution shall be free from suspended matter and 

 shall remain clear at all dilutions. 



Note. — Lime-sulphur from the chemical standpoint is exceedingly complex, 

 but it is clear that the purchaser should obtain only lime (calcium) and sulphur 

 in the solution (requirement a). He should also know that he is getting an 

 article sufficiently strong to make an effective spray fluid at the dilutions 

 usually advised (requirement b). Finally, since the active chemicals in the 

 solution are all soluble he should not be sold a proportion of inactive 

 " sediment " or " sludge " (requirement c). 



3. Nicotine. — It is proposed to deal under the Bill with 



nicotine when sold as such, but the exact requirements are still 

 under discussion. Purchasers of nicotine should, however, 

 note that while the term nicotine is properly applied to 

 the chemical in its free or uncomhined state, it is sometimes used 

 by sellers for combinations of nicotine with an acid — e.g., 

 nicotine sulphate. Nicotine sulphate is an excellent insecti- 

 cide, but it depends for its action on the nicotine it yields, 



