VOL. XIII.] PHILOSOPHICAL TRANSACTIONS. BSQ 



On the formation of Salt and Sand from Brine. Communicated by Dr. Robert 



Plot, S.R.S. N° 145, p. 96. 



Having strained a quantity of the brine, from the pits in Staffordshire, 

 through 8 folds of fine Holland, and as many more of finer cambric, yet no- 

 thing was left in this very close colander, but a little black dust, which was im- 

 puted only to the foulness of the water, it being nothing like sand; for having 

 examined the cloth both with the fingers and a microscope, there was found no 

 more of sand than if they had percolated the clearest spring water; and yet this 

 brine is found to hold in boiling at least \ of as much sand as salt, i. e. the brine 

 that suffices to make a bushel of salt, yields also at least a peck of sand. 



But notwithstanding this experiment, it did not seem necessary to suppose 

 that the sand was generated in the boiling, but might rather be originally there; 

 for before straining it there was observed in the water, by the help of a micro- 

 scope, a great multitude of very minute animals, much smaller than those in 

 pepper- water, swimming about in it, together with many small transparent 

 plates, some a little larger than the animalcules, and some less, but all of a 

 rectangular oblong figure, though some indeed seemed very near a square, 

 which were found also in the water after straining, as thick as before, the pores 

 or rather interstices between the threads of the Holland and cambric, though 

 they were extremely fine, appeared in the microscope to be 20 times greater 

 than either the animalcules or plates. And these were judged to be the original 

 particles both of the salt and sand ; which, as the water evaporates in boiling 

 might gather together till they made up such a visible course body, as the 

 greater corns of each are. And this suspicion was confirmed in a little time; 

 for observing with an excellent microscope some of the strong brine which 

 drops from the baskets or barrows, when the salt is first put into them, though 

 at first it looked like clear water, yet on a more accurate observation it appeared 

 exceedingly full of these oblong particles, which were perceived to gather together 

 and unite to form larger parcels; and, as the water dried off from the glass to 

 grow far larger till they appeared to equal, and not much unlike a large sized 

 diamond: which induced a suspicion that the sand might be also generated after 

 the same manner, it appearing to be only an insipid salt, composed of parts not 

 so sharp pointed as the others, but rounder and blunter angled, and conse- 

 quently not so pungent on the tongue. Yet this sand could not be made to 

 dissolve in water to any considerable quantity : and though the salt might dis- 

 solve in a small degree, yet it did not form itself again into plates. 



