307 
powder, since in this case the product is lumpy and makes a mixture 
of poor quality that clogs the nozzle badly. The milk of lime obtained 
should be of the consistency and have much the appearance of thick 
cream, and should be free from granules when felt between the fingers. 
In slaking a small amount of lime, such as 1 or 2 pounds, the mistake 
may easily be made of adding too much water and thus greatly retard¬ 
ing the action. In such cases it is best to use hot water, adding it 
little by little as it is absorbed. There is very seldom any difficulty in 
getting large amounts of lime to slake. 
STOCK MILK OF LIME. 
It has been Hound that the stock method, so valuable with copper 
sulphate, can be used with equal advantage for the lime. A barrel is 
taken, the capacity of which has previously been carefully determined, 
and twice as many pounds of stone lime are placed in it as it holds gal¬ 
lons. The lime is then slaked. If the slaking has been properly done 
the milk of lime will fill two-thirds to three-fourths of fhe space; then 
water is added to bring the milk of lime up to the mark. After stir¬ 
ring thoroughly a gallon will contain the equivalent of 2 pounds of 
fresh lime.* It is essential that the milk of lime be well stirred, pref¬ 
erably with a broad paddle. If the clear liinewater be taken it will 
contain only about £ ounce of lime instead of 2 pounds. However, as 
the slaked lime is only a jbrifle more than twice as heavy as the 
liquid and is in an extremely fine state of subdivision, it is found 
easy in practice to stir up the milk of lime in a few moments, so 
that it is of practically uniform composition throughout. The stir¬ 
ring must be repeated each time a quantity is dipped out. In settling, 
the lime leaves a clear layer of liinewater above. This contains about 
1 part in 800 of slaked lime in solution and absorbs carbonic acid 
readily from the air, forming a pellicle over the surface. The barrels of 
stock lime should be kept as closely covered as possible, though if not 
jarred the loss from this source is certainly very small in the course of a 
few days or weeks. However, it is best to slake all the lime as soon as 
received, and in case the barrels of stock lime have to stand more than a 
fortnight before being used, the barrel should beheaded up tightly and 
either the head kept covered with water or the whole buried in the 
ground, as suggested by Mr. Waite. 
PROPER RATIO OF LIME TO COPPER SULPHATE AND MEANS OF TESTING 
THE MIXTURE. 
The almost universal practice in this country has been to use 4 pounds 
of lime to G pounds of copper sulphate. There has been advocated of 
* In case the stock milk of lime is to he used at once, it will be necessary to allow 
it to cool, since the heat liberated during the slaking makes it very hot, and Bor¬ 
deaux mixture made hot is different in composition, settles rather quicker, and is 
doubtless decidedly inferior to the mixture prepared at ordinary temperatures. 
