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is likely to be more or less affected by the air, and does not 

 slake as well. 



Masons who are familiar with the use of lime utilize the 

 whole contents of a barrel for ordinary purposes. When, 

 however, it is necessary to prepare whitewash or finishing 

 material for plastering, they select nothing but the freshest 

 and finest lumps to slake. By this practice they obtain a 

 pure white, thoroughly slaked, pasty substance, fairly free 

 from grit. 



Particular attention should also be paid to the matter of 

 slaking the lime, inasmuch as a novice cannot do this prop- 

 erly. When the requisite amount of lime has been weighed 

 out, place it in a tub and add water cautiously, and only in 

 sufficient amounts to insure thorough slaking. It should 

 not be allowed to become too dry, neither should it be del- 

 uged with water. Lime slakes best when just enough water 

 is added to develop intense heat, which renders the process 

 active. When very small quantities of lime are to be slaked, 

 better results can be obtained by using hot water as a starter. 

 It is not desirable to stir the lime more than necessary when 

 slaking. If large quantities of Bordeaux are used, a stock 

 of slaked lime of the consistency of paste can be made, which 

 always should be covered with water, to prevent becoming 

 gritty. 



The copper sulphate or blue vitriol is dissolved in hot or 

 cold water, using either a wooden or earthen vessel. The 

 proper mixing of the two solutions is important. In mix- 

 ing, it is best to dilute both the copper and lime with water, 

 so when combined they will make the required amount. 

 Strain the lime, and mix the two solutions quickly and thor- 

 oughly together in a separate barrel. 



If the amount of lime is insufficient, there is danger of 

 burning tender foliage. In order to obviate this, the mix- 

 ture can be tested with a knife blade or with ferro-cyanide 

 of potassium (1 ounce to 5 or 6 ounces of water). If the 

 amount of lime is insufficient, copper will be deposited on 

 the knife blade, while a deep brownish-red color will be im- 

 parted to the mixture when ferro-cyanide of potassium is 



