358 



Wmte7' Cover Washes 



Method 

 added (in this case ^rd total 



is allowed to "dry slake." From previous trials, wet slaking, namely 

 covering the lime completely with water, promised the best results. 

 Taking always lime two parts to water ten parts by weight the 

 following ways were tried : 



No. 



(1) Excess of hot water 



required) applied hot 



(2) Ditto but applied cold 



(3) Excess of cold water added 



(4) Slaked dry with cold water. Then full quantity added 

 (6) Slaked dry with hot water. Then full quantity added 



In these trials hot water gave decidedly the best result. This is probably 

 owing to the completeness of slaking thus obtained. Accordingly, 

 further trials were made with the object of getting conditions which 

 should give complete slaking. 



The following methods were tried with the results as given in the 

 table below: 



Result 

 Good coat 



Not quite so good 

 Decidedly inferior 

 Poor 

 Poor 



No. Method 



(1) Made up with hot water and not allowed 



to stand 



(2) Made up with cold water and not allowed 



to stand 



(3) Slaked with | full quantity cold water. 



Left for 12 hrs., remaining water added 

 and applied 



(4) Made with full quantity cold water. Left 



for 12 hrs. and applied 



(5) Dry slaked and left for 12 hrs. Then 



made up to full amount of water and 

 applied 



(6) Made up to full dilution and allowed to 



stand for 12 days 



(7) Ordinary lime coating dried slowly in 



a moist chamber 



(8) Lime mixture left in small quantities in 



a large evaporating dish so as to dry 

 slowly 



Result 

 Thick but very brittle coat 



Not so thick or brittle 



Rather harder than (2) and slightly 

 brittle 



Fairly thick and not brittle 



Thin but firm coat 



The mixture became very flocculent 

 and the surface covered with a 

 layer of carbonate. When dried on 

 the slide it gave a very soft and 

 powdery coat 



It produced a hard marbly coat with 

 softer material underneath 



This produced an exceedingly hard 

 and firm coat 



The results from Nos. (1) to (5) clearly show that in cases where 

 the lime was slaked slowly, as when a dry slake was given or the mixture 

 allowed to stand for 12 hours, a firmer, less brittle coat was obtained 

 though not necessarily a thicker one. This result was afterwards 

 confirmed by trials in the field. A dry slake gives a very thin and 

 therefore unsuitable coat for an egg cover in practice. No. (8) gave 

 an excellent coat, no doubt due to its slow drying in an indoor atmo- 

 sphere containing more than the usual percentage of carbon dioxide. 



