J. V. EvKK AND E. 8. Salmon 479 



as "Cook's Soap." The sample was rather a fluid type of soft soap 

 which exhibited a neutral or sliiihtly acid character. The total alkali 

 was found to be equal to 11-6 % KOH (or 8-36 % NaOH). 



Saponin. The matei'ial used was the ordinary white powder sold 

 commercially. 



Liver-of -sulphur. Of several samples examined, one supplied by 

 Messrs Baird and Tatlock was selected as being a good sample and 

 suitable for the purpose of this worlc. It was found to contain 44 % 

 sulphur of which 42-2 % was present as sulphide-sulphur^ ■ less than 

 1 % as sulphate and less than 1 % as sulphite and thiosul]ihate. The 

 alkalinity was found to be ecpial to 4--^ % K^COo and the total alkali, 

 calculated as KOH, equal to .09-6 % — of which 48-8 % was due to 

 potassium. The sample may be considered to be a superior one to 

 anything likely to be purchased l\y the grower. 



Yellow ammonium sulphide. This material was prepared by satu- 

 rating 200 c.c. of a 10 % solution of ammonia in water at 17° C. with 

 sulphuretted hydrogen, then adding 400 c.c. of 10 % ammonia solution 

 and 1000 c.c. of water. To this mixture 24 grms. of flowers of sulphur 

 were added and when completely dissolved the clear solution constituted 

 the stock solution used throughout this work'^. The total sulphur 

 present in this solution was found to be 3-7 % of which 2-2 % was 

 present as sulphide-sulphur. Sulphates were absent and only traces 

 of sulphites and thiosulphates could be detected. The sp. gr. of the 

 stock solution was ]-001 at 1.5° C. 



Colourless ammonium- hijdrosulphide. This was prepared by satu- 

 rating a 4 % solution of ammonia in water with sulphuretted 

 hj'^drogen. The amount of "sulphide-sulphur'' which was present 

 was found to be 6-72 %. 



Colourless ammonium sulphide. The above solution of ammonium 

 hydrosulphide was mixed with an equal volume of 4 % ammonia 

 solution. The quantity of sulphide-sulphur was found to be 3-36 %. 



Lime-sulphur. Berger's brand of "lime-sulphur" was used and 

 diluted to the sp. gr. 1-01 and 1-005. At the former concentration 

 the amount of sulphide-sulphur present was found to be 1-43 %. 



' The estimation of sulphide-sulpliur was effected by the volumetric method in which 

 a standard ammoniacal solution of zinc is employed and a solution of nickel sulphate 

 used as an outside indicator. 



- The method followed in preparing the spray-fluids from the stock solution may be 

 illustrated in the case of that used in Expers. 9 and 10, p. 494, which was prepared by 

 diluting 25 c.c. of stock solution to 200 c.c. with distilled water and then adding 200 c.c. 

 of a 2 % solution of soft soap in distilled water. 



