SOLAR SALT APRONS 43 



space of 16 x 18 feet square or 288 square feet. The size 

 of the yard is estimated by the number of covers it has. 

 During fair weather the covers are pushed aside wooden 

 frames constructed for that purpose beside the rooms. 



SOLAR SALT " APRONS " 



Within the last 15 years, the Onondaga solar salt manu- 

 facturers have adopted a plan by which some of them have 

 increased their evaporating surface to a considerable extent, 

 namely, they have added to their works, according to the 

 space at their disposal, very large shallow vats from 20 to 

 100 feet wide by 200 to 2000 feet long and about 3 inches 

 deep. Wherever practicable they are erected over the deep 

 rooms (serving instead of roofs) thus making the latter 

 practically store rooms. These vats or aprons, as they are 

 called, are built in a similar manner to the vats previously 

 described, on piles or posts. At certain distances from each 

 other are two sets of holes provided with wooden plugs. 

 The surface of these flat vats is so constructed that any 

 brine or rain water on them will run rather slowly towards 

 these holes. One set of holes communicates with the deep 

 room. During fair weather a small quantity of brine is 

 allowed to run into these vats, not exceeding one half inch 

 in hight and it often becomes entirely saturated in one day, 

 when it is discharged into the deep room below, and its 

 place is taken by a fresh portion of brine to be evaporated. 

 In case rain is expected the plugs over the deep rooms or 

 cisterns are drawn, the brine runs off, the plugs are again 

 inserted and those drawn out of the other holes, through 

 which the rainwater runs off. 



The advantages of this method are: first, a much more 

 rapid evaporation due to the shallow layer of brine, and 

 secondly, the gain of all the lime rooms for salt rooms. 

 Ordinarily a solar salt yard with 2700 "Covers" 10 by 18 

 feet square, consists of 1800 salt rooms, 800 lime rooms and 

 100 deep rooms. By this improvement the salt rooms are 



