i'Aliisi-UllEKN. 81 



forming a deep blue solution, and capable of being diluted with water 

 without decomposition or precipitation. 



*' The fixed allialies, potash and soda, in strong aqueous solution 

 decompose this poison, the blue hydrate of copper separating. This on 

 heating first becomes changed into the black oxide, and finally the 

 red cuprous oxide, the arsenic going into the solution as potassium 

 arsenite. 



• ' A number of experiments have been tried as to the solvent action 

 of different soap solutions on this insecticide. The soaps used were 

 (1), whale-oil soap; (2), common brown soap ; (3), 'English' soft- 

 soap. 



" The whale-oil soap strength (1 lb. to 8 gallons of water) was not 

 alkaline to test paper. The Paris-green was shaken up with this 

 solution repeatedly for five days, and the mixture then filtered. Not 

 a trace of arsenic could be detected in the filtrate, showing that no 

 decomposition of the Paris-green had taken place. The latter retained 

 its bright green appearance throughout the experiment. 



" The solutions of the ' common brown ' soap, and ' English ' soft- 

 soap, were not of any stated strength, but were as strong as it was 

 possible to make them. By this means, a severe and extreme test was 

 made in each case. 



" The common brown soap was strongly alkaline. Its solution was 

 found to slightly decompose the Paris-green, arsenic being detected in 

 the filtrate in traces after acting upon it for five days. The residual 

 Paris-green was, however, bright green, which, together with the fact 

 that but traces of arsensic passed into solution, shows that only to a 

 very slight degree had the poison been acted upon. 



" With the ' English ' soft-soap solution, which was much more 

 strongly alkaline than the preceding, there was more decomposition, 

 i. e., more arsenic passed into solution, and more copper precipitated, 

 than in the experiment just cited. The treatment was similar as in 

 the previous trials, and the result showed that heavy traces of arsenic 

 had passed into solution, while at the same time a slight brown deposit 

 of oxide of copper was to be noticed on the residual Paris-green. 



" If it were necessary for the efficacy of the poison that the Paris- 

 green be applied in such liquids as would have no decomposing or 

 solvent action upon it, the results of these experiments show that no 

 practical harm or deterioration would result from using it with soap 

 solution. When it is remembered, however, that Paris-green, though 

 insoluble in water, passes, more or less rapidly, into solution by the 

 action of the digestive fluids before its toxic effects can be conveyed 

 throughout the insect's body by the circulatory system, there seems 

 to be no good ground for condemning an application in which traces 

 of arsenic are already soluble. The chief reason against the use of 



