144 The Spraying of Plants. 



potassium test is of value. The kerosene emulsion should be 

 made according to the Hubbard-Riley formula, and then be 

 poured into the Bordeaux mixture. And finally the arsenite 

 may be added. Unfortunately, even if the combination be 

 successfully made, the various ingredients appear to lose much 

 of their value when so applied, and as yet the preparation 

 cannot be generally recommended. 1 



CORROSIVK SUBLIMATE. See MERCURIC CHLORIDE. 



CUPKAM. A term applied to copper carbonate dissolved in 

 ammonia, which see. 



CUPRIC STEATITE. See SULPHOSTEATITE. 



CUPROSTEATITE. This powder closely resembles sulphostea- 

 tite in its composition, but while the latter contains about 10 per 

 cent of copper sulphate, the copper in cuprosteatite is in the 

 form of the hydrate, about 15 per cent of the powder being of 

 this material. On this account the fungicide is said to be 

 less caustic to foliage than sulphosteatite. Both powders are 

 applied in the same manner. 



CYANIDE OF POTASSIUM. See HYDROCYANIC GAS. 



DALMATIAN INSECT POWDER. See PYRETHRUM. 



DAVID'S POWDER; DRIED BORDEAUX MIXTURE. The old 

 formula for preparing the powder called for 



Copper sulphate 4 pounds. 



Quicklime 1(> pounds. 



As little water as possible was used for dissolving the sul- 

 phate and for slaking the lime ; the two were then united and 

 the product dried. It was then ground to a powder and ap- 

 plied. The ingredients used at present in making the Bordeaux 

 mixture can be similarly treated. When the dried mixture is 

 used in place of that suspended in water, it has been found that 

 about four times the amount of the materials is required, and 

 the distribution is on the whole not so satisfactory. The pow- 

 der has never been used to any great extent, and for the reasons 

 given will probably never become popular. 



EAU CELESTE (Audoynaud process). 



Copper sulphate 1 pound. 



Hot water 2 gallons. 



1 See also Slingerland, Science, xxii. No. 551, 105. Also, Bailey, Annals Hori. 

 1893, 43. 



