82 LAKES OF NORTH AMERICA. 



such observations as bear on tlie question, it seems safe to assume tliat 

 their mingled waters would contain less than double the percentage of 

 saline matter found in the surface streams. The assumption that the 

 combined spring and stream waters would contain about 0.3 part in a 

 tliousand, or three one-hundredths of one per cent of total solids in solu- 

 tion, seems as close an approximation as can now be reached. 



The waters of the lake during recent low stages have become nearly 

 saturated with sodium chloride and sodium sulphate, and under certain 

 conditions these salts are precipitated. The point of saturation for 

 calcium carbonate is passed, and this salt is precipitated })robably as 

 rapidly as it is received. The waters are not rich in the compounds of 

 bromine, boron, lithium, and iodine, winch frequently occur in " mother- 

 liquors," remaining when the more common salts have been eliminated by 

 long concentration, and hence indicating the old age of a lake containing 

 them. The recent anal3'sis by Waller, however, shows these rarer elements 

 to be present in somewhat larger quantities than was previousl}" supposed. 



The length of time that would be required to charge Great Salt lake 

 with the common salt it contains, under the present conditions, is estimated 

 by Mr. Gilbert at about 25,000 years. 



The quantity of sodium chloride, or common salt, held in the water 

 of the lake is estimated at 400 million tons, and the sodium sulphate at 

 30 million tons. These figures indicate the commercial importance of 

 this great reservoir of brine. The separation of the common salt has 

 already led to a considerable industry, as from 20 to 40 thousand tons 

 have been gathered yearly for a considerable period. The most extended 

 and best conducted of these operations are carried on by the Inland Salt 

 Company at the southern end of the lake. Evaporating vats covering 

 more than one thousand acres have been constructed, and are supplied by 

 pumps which deliver 14,000 gallons of lake water per minute. Pumping 

 is continued through May, June and July, and the salt is ready for gather- 

 ing in August. During midsummer the amount of water evaporated is 

 8,400,000 gallons daily. The yield of salt is at the rate of 150 tons per 

 inch of water per acre. An average season's yield is a layer of salt about 

 seven inches thick, which would be precipitated from forty-nine inches of 

 water. The facilities for this industry may be judged by the fact that 

 coarse salt packed on cars ready for shipping, is sold at the works for one 

 dollar per ton. The mother-liquor is allowed to go to waste, but it is to 

 be expected that sodium sulphate and other salts contained in it will be 

 utilized in the near future. 



