DITLilON OF CHEMISTRY 125 



SESSIONAL PAPER No. 16 



Detailed eonnnent on the^e data is unnecessary, but it may be pointed out that 

 those pastes containing the least water and the smallest perceirtages of soluble arsenic 

 oxide are, other things being equal, of the best quality. 



We may be permitted to repeat that the practice foUowed by some manufacturers 

 of putting a guarantee on the label, stating the percentage of arsenate of lead and 

 particulars as to soluble impurities, is to be commended. It would allow the purchaser 

 to judge of the relative merits of the various brands offered on the market. 



Formaldehyde. 



From time to time, samples of formaldehyde are sent in by farmers and agricul- 

 tural organizations in the northwest, for examination. Occasionally we have found 

 a sample below standard strength but these, as a rule, have been taken at retail stores, 

 from bulk ; those drawn from the original containers have almost invariably conformed 

 to the guarantee. We have no evidence, therefore, that the manufacturers are put- 

 ting out a product below the standard though, as might be expected, all brands are 

 not identical in the percentage of formaldehyde they contain. 



Formaldehyde 

 by weight. 

 Laboratory Ko. ~ Per Cent. 



14030 contains 37 17 



14256 " 38-21 



14257 •' 37-51 



It is evident from these data that there had been no adulteration, the standard 

 strength calling for 40 per cent by volume which is, approximately, 37.3 per cent by 

 weight. They all conform with the guarantee. 



The turbidity or milkiness observed in some samples is due to a slight ' polymeri- 

 zation ' or the conversion of a part of the formaldehyde into a solid form. We have 

 no data that would allow us to make any definite or final statement regarding the 

 effect of slight polymerization on the value of the solution for destruction of smut in 

 grain but such experience as we have had has not shown that there is any marked 

 falling-off in fungicidal value. 



PINE SPRAY INSECTICIDE. 



Lahoratory No. ISOJfS, submitted by the Horticultural Division and forwarded 

 for trial by Robinson Bros., Ltd., W. Bromwich, Staffs, England. It had the 

 a])pearance of a strong soap solution and possessed a markedly alkaline reaction. 



Analysis. 



Per Cent 



Moisture and loss at 100 degrees C 70-4 



Total oil or fat 25-7 



Total alkali, all potash 2.45 



By distillation — 



Water 62.0 



Light oils 8. 



This is evidently an aqueous solution of a potash soap containing a certain 

 percentage of light oils. 



It may be noted that emulsions and sprays made with a potash soap possess 

 better spraying qualtities than those made with a soda soap. 



WORM KILLER. 



Lahoratory No. 150Jf3. — Submitted by H'orticultural Division and also for- 

 warded by Eobinson Bros., Ltd. It is a clear, magenta colored liquid, with a slight 

 deposit. 



