11 Nov., 1918.] Copper Fungicides for Vine Diseases. 677 



To properly slake lime it should be sprinkled with a little water, but 

 not completely submerged, and left to itself for half an hour or so. 

 During this time it swells up considerably, cracks and crumbles, and 

 finally falls into powder, hissing, and giving off steam, owing to the heat 

 generated by the reaction. When thoroughly slaked the requisite quan- 

 tity of water should be added to make the stock milk or cream described 

 above. 



The stock milk can with advantage be prepared sometime before 

 use ; if too fresh it contains numerous gritty particles usually known 

 as " core " ; this mainly consists of fragments of lime as yet unslaked. 

 It is well known by plasterers that freshly prepared " lime putty " 

 often " blows " after being spread on the walls, owing to the belated 

 slaking of particles of lime ; similar trouble does not occur if the putty 

 was prepared some time previously. Once made up, the lime milk will 

 keep in good condition, at any rate for a few days. It really consists 

 of lime-water containing an excess of lime in suspension; on resting, 

 the suspended lime falls to the bottom to form a sediment which is pro- 

 tected from the air by the supernatant lime-water. It is true this 

 becomes slightly carbonated on the surface, as is shown by the forma- 

 tion of a slight glassy film, but the deterioration on the whole is very 

 slow. 



It is possible that the method of treating lime usually followed by 

 plasterers, may prove a very convenient way of handling lime in 

 order to have on hand a stock always ready for immediate use, and 

 which will keep in good condition and reasonably free from carbonate 

 for several weeks. ''Lime putty " is the name given by plasterers to a 

 stiff paste of about the consistency of butter, made by mixing freshly- 

 slaked lime with a sufficient quantity of water. It may vary a good deal 

 in composition; naturally, the stiffer it is the richer in lime. When of 

 the consistency usual in France, it is estimated to contain lime equiva- 

 lent to 20 to 25 per cent, of pure quicklime.* On this basis, the quantity 

 required for each 50-gallon lot of " Bordeaux " would be from 9 to 11-| 

 lbs. If lime putty were made up to a definite standard of consistency, a 

 measured quantity of it could be taken for each 50-gallon lot of spray 

 mixture. The quantity required could be easily detennined with the 

 aid of phenolphthalein test paper when making up the first lot. A large 

 garden trowel would be a convenient measure. For subsequent lots it 

 would only be necessary to take the requisite number of trowelfuls, 

 dilute it in a bucketful of water, and mix into the Bordeaux in the 

 usual way. It would be well to check occasionally, the commencement 

 of alkalinity, with phenolphthalein paper. 



As lime putty appears to keep with very little change for scA^eral 

 weeks, a fair stock of it could be made up at one time. 



Hydrated Lime. 



This substance, which is none other than very carefully slaked lime, 

 is largely used in the United States in connexion with cement manu- 

 facture, and for other industrial purposes; it is also becoming popular 

 with plasterers in America. 



" Hydrated lime is the powdered product formed by slaking 

 quicklime with the requisite amount of water. The material, as it 



* Ravaz. Progres Agricole, 16th August, 1918 : — " As regards slaked lime in the form of thick 

 pastes, these contain from 75 to 80 per cent, of their weight of water. 



