125 



and on repeating the process several times a little high, show- 

 ing incomplete washing. 



Without recording all the experimental work, it was 

 found that thorough washing by decantation is necessary to 

 remove all free alkali. That just as quick saturation may 

 be secured at ordinary room temperature as by dissolving cold, 

 and that if proper precautions are taken uniform results can 

 be secured at a temperature not exceeding twenty-five and not 

 below twenty-two (71 to 77 Fah). 



The average of several closely agreeing figures for differ- 

 ent lime, in which the temperature was not the controling ele- 

 ment, gave a solubility of .1265 Gms. per one hundred, or forty- 

 five per cent of and n-10 solution or 10-222 normal solution. 



Using my results as a criterion Lamy and Maben are too 

 low, probably due to contact with CO 2 during filtration as in 

 my work with so-called chemically pure lime, working with 

 comparatively small quantity. Guthrie's results are reason- 

 ably comparable with mine; are the latest results at hand and 

 may be given more credence than older analyses. Holm's are 

 certainly too high, the unwashed lime being probably contam- 

 inated with alkali carbonates. It should also be mentioned 

 that the temperature employed by Holm is much below the 

 usual temperature of working rooms in this climate. 



My experiments do not justify the assertion that the loss 

 by absorption of CO 2 is immediately corrected by further so- 

 lution of the lime. However, if the contents of the bottle 

 are thoroughly agitated and allowed to stand a day or two 

 saturation is again obtained. 



As a working method for the preparation of standard 

 lime water, I would advise this procedure: 



Slack a pound or two of fresh lime in a gallon or larger 

 vessel, by adding double volume water. Fill with water and 

 stir; cover; allow to thoroughly settle and pour off as much 

 clear solution as possible. Repeat three or four times. Trans- 

 fer the fine lime to a large bottle (the larger the better) throw- 

 ing away any lumps which may be present. Wash again in 

 bottle with ordinary well water, or better, rain water. Fill 

 nearly full and shake at intervals for several hours, at tem- 

 perature between twenty-two and twenty-five degrees C., pre- 

 ferable the latter. Allow to stand at least two days (stop- 

 pered, of course) when it is ready for use. 



