171 



or the bruised parts of the bonnes : 5. Some of these were 

 so bright, tha-t holding a printed paper to them I could 

 read several letters : b One could not discern in any of 

 thi: m the least degree of heat, neither of putrefaction : 

 7- One of these being put in a cup of coid water, the 

 light continued the same. 



Not only water, fish and flesh, but some sort of iroo-i 

 will shine as bright as a burning cnaL And herein they 

 agree, I. Both have light in themselves : 2. Both need 

 the air, to make them continue shining : 3. Both having 

 lost their light, by being deprived of air, recover it, 

 when fresh air is let in : 4. Both are easily quenched by 

 water, and 5. Neither of them is affected by the cold- 

 ness of the air. 



But herein they differ: 1, The light of a coal is put 

 out by compression : that of wood is not : 2. The coal 

 is quite extinguished by withdrawing the air : that of the 

 wood is only eclipsed : 4<-t t.li air in again within half 

 an hour, and it immediately recovers : 3. A coal put 

 into a small, close glass, will not burn many minutes: a 

 piece of wood will shine many days : 4. A burning coal 

 emits much smoke, shining wood none at ail. 



A diamond, by an easy friction in the dark, by the 

 finger or a woollen cloth, appears in its v\hole body to 

 be luminous : and if it has been rubbed a good while, 

 it will keep its light for a little time. If when the sun K 

 set, one holds up a piece of flannel stretched tight be- 

 tween both hands at ^a little distance, and another rubs 

 the diamond swiftly a-nd strongly on the other side of it, 

 the light to the eye of him that holds the cloth, seems 



uch more pleasant and perfect. What is more sur- 

 prising, is, that a diamond exposed to the open air, in 

 view of the sky, (even without being in the sunshine) 

 gives nearly the same fight of ilyelf without rubbing, as 

 when rubbed in a dark room. But if you hold your 

 hand or any thing else over it, to hinder its communica- 

 tion with the sky, let it lie ever so long in the open air, 

 yet it will give no light. 



VOL. in. r 



