84 Annals of Horticulture. 



''Among the powders, the sulfosteatite and the cuprostea- 

 tite proved to possess the greatest adherence, and conse- 

 quently, in case of an attack they would have protected the 

 vines longer than the other substances. The principal ingre- 

 dient of these powders is talc, which, when dry, has the 

 greatest adhesive power. But while the sulfosteatite natur- 

 ally contains only lo per cent, of sulphate of copper, the cu- 

 prosteatite has 15 per cent, in the form of hydrate of copper, 

 and consequently it cannot burn, as sometimes occurs with 

 the sulfosteatite. 



"We have frequently called attention to the danger of us- 

 ing substances containing soluble sulphates. The danger is 

 increased when the powders contain sulphate of copper in a 

 natural state, however finely divided. When a drop of w^ater 

 dissolves one of these particles a concentrated solution is im- 

 mediately formed and this has an exceedingly caustic action. 



"The squares upon which the liquids had been applied re- 

 ceived the last application July 25. The summer rains soon 

 washed away all traces of the Bordeaux mixture and shortly 

 afterwards of the other materials also, excepting two. The 

 mixture of carbonate of soda and sulphate of copper resisted 

 the action of the weather admirably, but the stains of verdet 

 showed plainly upon the leaves even after they had fallen in 

 November. Like results have been obtained wherever the 

 verdet has been tried, and thousands of acres have been treat- 

 ed with it. This property of the verdet is of prime impor- 

 tance, for we are thereby enabled to make fewer applications 

 and these retain their efficacy for an indefinite period. Three 

 applications were made, in order to reach the later growths of 

 the vine. 



"The above observations have led Mr. Duchein to arrange 

 the liquids in the following order, based upon the length of 

 time during which they remain effective : 



"I. Verdet. 



"2. Carbonate of soda and sulphate of copper. 



" 3. Improved Bordeaux mixture. 



"4. Sulphocyanide of copper (liquid). 



"5. Eau celeste. 



"6. Gelatinous hydrocarbonate of copper. 



"7. Aluminium mixture. 



"8. Bordeaux mixture and sporivore. 



"q. Bordeaux mixture. 



