6l6 PHILOSOPHICAL TRANSACTIONS. [aNNO i76^. 



which is really true ; but cannot be seen till the animals grow faint for want of 

 water ; then, if we attend, we may, with good glasses, plainly discover them.* 



I come now to a singular property, which I have discovered in hempseed, of 

 producing an indissoluble salt, when infused for some time in water : and as 

 hempseed is known to be an efficacious medicine in some particular cases, these 

 experiments may demand a stricter inquiry from the professors of physic, which 

 may possibly turn to the benefit of mankind. 



Exper. I. On Feb. 25, last, Mr. E. put half an ounce of hempseed to about 

 2 ounces of New-river water in a phial, and covered it close with paper, to pre- 

 vent the dust coming to it : by the 25th of March it became very putrid, and 

 had thrown up a viscid scum to the top. Fahrenheit's thermometer in the house 

 was, during this time, from about 44 to 52 degrees. He examined this scum 

 with a common magnifier, of about an inch focus, and could discover it to be 

 full of regular-shaped salts, which lay on the surface ; some of a square, others 

 of an oblong figure. Applying some of the scum to a slip of glass, he placed 

 it in the single or Wilson's microscope, making use of the 4th magnifier, and it 

 exhibited the crystals represented at fig. 7> pi. 18 ; but as the stirring of the 

 scum had obscured the precise figure of the salts, he applied a hair pencil to 

 them, dipt in clean river water, and separated them from the mucilage that had 

 besmeared them ; yet, notwithstanding this addition of water, their figures were 

 not in the least impaired or melted, but their outlines were rather more exactly 

 defined. Nor were the millions of minute animals that were swimming over 

 them, and all round them, in the least affected by the salt.-l" 



Mr. E. further observed, that the crystals that appeared, first increased in size, 

 and began to vary their forms; for instance, many of the crystals, at the latter 



* I have lately found out, by mere accident, a method to make their fins appear very distinctly, 

 especially in the larger kind of animalcula, which are common to most vegetable infusions, such as 

 the terebella j this has a longish body, with a cavity or groove, at one end, like a gimblet : by 

 applying then a small stalk of the horse-shoe geranium, or geranium zonale of Linnaeus, fresh 

 broken, to a drop of water in which these animalcula are swimming, we shall find, that they will 

 become torpid instantly, contracting themselves into an oblong-oval shape, with their fins extended 

 like so many bristles all round their bodies ; the fins are in length about half the diameter of the 

 middle of their bodies. Before I discovered this expedient, I tried to kill them by different kinds of 

 salts and spirits ; but though they were destroyed by this means, their fins were so contracted, that 

 I could not distinguish them in the least. After lying in this state of torpidity for two or three 

 minutes, if a drop of clean water is applied to them, they will recover their shape, and swim about 



immediately, rendering their fins again invisible. For the different states of this animalcule, see 



fig. 5, a, b, c, d. — Orig. 



+ Mr. Needham observes, m his curious Memoir before mentioned, p. 649, I'l^f "^'t destroys 

 these animalcula ; this, I believe, is very true of the common kinds of salt ; and which renders the 

 nature of this kind of salt still more singular.— Orig. 



