VOL. XXIV.] PHILOSOPHICAL TRANSACTIONS. 101 



out being above to discover any particles in it, which I conceived to consist of 

 coagulated salts ; and that there were some such under the scum, but they 

 were so obscure that I could not well perceive them ; and the more, as they 

 were hid by the scum. 



I took then a larger piece of the abovementioned stone, and heating it red 

 hot, I let it fall into the water also ; on which there came a thicker scum over 

 the water, which I let lie upon it 24 hours, and then breaking it, and taking 

 a little out of the water, 1 found it hard and petrified ; and placing it before the 

 microscope, to discover, if possible, the figure of those particles, I could not 

 however accomplish my intentions, though I ofien repeated the trial, by reason 

 of the smallness of the particles, and their strict union with each other ; only 

 a few of them appeared to be 4 and 6 sided, and to reflect the light from so 

 many parts ; others, that were larger, were composed some of 3, some 4 

 smaller particles, which we may thus reckon to be salt ones. Several thousands 

 of these small particles lay in a very small space ; which being separated and 

 broken in pieces, I judged that each particle consisted of many more, and 

 much smaller ones ; and indeed they were so minute, that they almost escaped 

 my sight, through the best of my microscopes. I tried some of the same par- 

 ticles in a pretty strong fire, and found that they lost some of their transparency, 

 and were divided into particles, that were quite dark and obscure. 



After this, I took a Utile of that water which lay under the surface of the 

 supposed coagulated salts, imagining I should find some salt particles in it, and 

 putting it upon 3 clean glasses, I observed that after the space of 4 hours, 

 the water was quite exhaled, and that there remained many thousands of salt 

 particles out of one single drop of water ; which salts were all separated from 

 one another, many of their surfaces being very bright, but their sides dark ; 

 and I could clearly perceive that some of their surfaces were shining, and their 

 figure quadrilateral : the darkness of their sides I judged to be, because those 

 salts were squares, in shape like dice ; between these lay other particles, that 

 were much smaller, and 1 believe of the same figure too, but because of their 

 smallness I could make no certain judgment of them. 



After the water, which lay very thin, was suddenly exhaled, I saw several 

 salts that were larger than the rest, and more irregular in their figures, but co- 

 agulated together, some of which were squares, but not regular. I took about 

 ten times as much rain water, and mixed it with the salt water, and then ob- 

 served that the salts were not dissolved, but emerged to the top of the water ; 

 but when I pressed the same salt particles under water, so as to wet them all over, 

 they subsided to the bottom, and remained there, without being dissolved, op 

 uniting themselves to the water. 



