PHYSICAL AND LITERARY. 37! 



to overcome the force by which the par- 

 ticles of fak-petre cohered with one ano- 

 ther. 



If a known quantity of cold water has 

 diflblved as much lalt petre as it is capa- 

 ble to hold, in this folution, the water is 

 to the fait as 5! to i ; (in fcalaing wa- 

 ter, the proportion is as 4 to i-). If then 

 I of the water is wafted by evaporation, 

 many of the fmall particles of nitre, being 

 brought into contad, join together, and 

 form chryftals in ihape and other proper- 

 ties refembling the nitre which was dif^ 

 folved in the water. It follows, there- 

 fore, that the particles of nitre mutually 

 attrad one another, when the interpofing 

 matter is removed^ the diftance betwixt 

 them very much diminifhed, and no fu- 

 perior power adling upon them ; and. 

 when in contact, they cohere with a cer- 

 tain degree or force. Again, it appears, 

 that the particles of water do attrad the 

 particles of nitre more ftrongly than thefe 

 laft attrad one another; and, coniequent- 

 ly, overcome their cohefion, and fufpend 



thcif 



