182 



EXPERIMENTAL FARMS 



Laby 

 No. 



5977 

 5656 

 5657 

 5G58 

 5978 



9-10 EDWARD VII., A. 1910 



Analyses of Acetate of Lead. 



Description. 



Insoluble 



in 



water. 



Baker and Adamson (C.P.) C. &. S. S. Co 

 Mercks (C. P.) W. E. Saunders & Co.. . . 



' Brown,' Lymans, Limited. . 



' White Crystals ' Lymans, Limitad. . . . 



' Powdered ' Lymans, Limited 



'Commercial' W. E. Saunders & Co.. . 



% 



•27 

 •27 

 3-81 

 ■29 

 •39 

 •20 



Lead 

 Oxide. 



% 



60-19 

 59 93 

 57 -72 

 58-35 

 58-23 

 58 07 



ARSENATE OF SODA. 



This chemical is found in two forms — crystalline and dry — the former naturally 

 containing less arsenic. From our analyses (see subjoined table) a very fair degree 

 of uniformity is to be observed in the crystalline variety as regards percentage of 

 arsenic oxide, the constituent which determines the strength of the sample for our 

 present purposes. 



The case, however, is not so simple with arsenate of soda in the ' dry ' form, 

 for it is evident from the samples analysed that this is not a compound of constant 

 composition. Thus we find in the three samples analysed amounts of water varying 

 from 5-15 per cent to 27-59 per cent. This variability of composition is undoubtedly 

 due to the temperature employed in the drying of the chemical and the difficulty is 

 that the purchaser is not aware in buying the ' dry ' form to what extent the material 

 has been modified. This fact, of course, maizes it impossible to state with precision 

 the amount of the so-called ' dry ' arsenate of soda to be used in the formula. The 

 ' dry ' arsenate of soda is also sold under the names ' crude ' and ' anhydrous.' 

 fhe term commercial is used for both the crystalline and dry arsenate, the latter, 

 however, is easily distinguished from the former by being in the form of a powder. 



Analyses of Arsenate of Soda. 



Laby 

 No. 



Description. 



5979 

 5980 

 5982 

 5763 

 5730 

 5983 



' Com'l Crystals,' W. E. Saunders & Co 



' Pure Crystals, ' ^lercks 



' Puie Dry B P.'Mercks.". '.'.'.'.'.'.'.'. ' ". .'.'.'.". 

 ' Com'] Dry Powdered,' Lymans Limited .... 



II 11 Powers Weigh tmanllosen- 

 garten 



Arsenious 



oxide. 

 (AS2O,). 



% 

 None. 



-55 

 6-35« 



8 -sot 



* The total arsenic in No. 5730, is equivalent to 60-91 per cent arsenic oxide. 

 tThe total arsenic in No. 59S3 is equivalent to 01 03 per cent arsenic oxide. 



Laboratory experiments have been conducted by us, using both forms of arsenate 

 of soda, to ascertain the proportions in which the chemicals must be employed in the 

 correct preparation of the spray. From the results the following formulae have been 



