95 



Notes on " Salt Lime. 



Fra.nk B. Wade. 



"Ye are tlie salt of the earth: hut if the salt have lost his savour, 

 wherewith shall it be salted? it is thenceforth good for nothing but to be 

 east out and trodden under foot of men." — ^Matthew, v, 13. 



This passage from "the [<ermon on the Mount" has doubtless puzzled 

 many a chemist, for salt ^^•ithont savour is as much an anomaly as a smile 

 (s'ithout a face. 



Last summer, while sjiending my vacation at the seashore, I came 

 across an old-fashioned "salt works." where common salt is prepared- by 

 evaporation of sea water, partly by means of trickling it over masses of 

 brush and further by solar evaporation in shallow vats. 



It was while investigating the process that I came upon what seems 

 to me to be a plausible explanation of the scriptural passage, and at the 

 same time I secured a quantity of the material called by the salt makers 

 "salt lime," which is the subject of this paper. 



It seems that the first solid product to separate from the sea water 

 upon concentration by evaporation is a very slightly soluble, white, crystal- 

 line substance, which gathers in the first four or five shallow vats. These 

 are provided, so that the tasteless, gritty substance may not come down 

 along with the salt and constitute an undesirable impurity in it. This 

 tasteless substance is "salt lime." 



As to the connection between this substance and the salt which had 

 lost its savour, 1 think it very probable that the ancient salt makers omit- 

 ted to provide separate vats for the first, very slightly soluble product, and 

 that as a result it got mixed up with their salt. Then, possibly, owing to 

 exposure to moisture, the real salt may have become dissolved away from 

 this less soluble part in certain instances, and the residue, being tasteless, 

 would naturally be supposed to liave "lost its savour," by the unscientific 

 mind of that time. 



Having secured eight or ten pounds of salt lime, I made an examina- 

 tion of the substance to determine its nature. 



In physical ap]iearauce it is grayish white in color, crystalline in struc- 



