MLISHA MITCHELL SCIENTIFIC SOCIETY. 67 
His explanation of the difference in the specific gravity 
of various bodies is based upon this theory of voids. 
Why do some things excel in weight others 
Of greater size? If equal matter be 
In globe of wool and lead, why equal not 
In what to matter most essential is— 
Weight? Downward pressing to the void unknown, 
The greater lighter than the less, thus prove 
Existence of a void, the heavier still 
Embracing less than light of spaces void. 
Book I p. 49. 
From his standpoint-the weight was dependent upon 
density or compactness. From this is it might be inferr- 
ed that all atoms had the same weight. 
The beautiful phenomenon of the condensation of moist- 
ure upon a cold surface is correctly explained if we dis- 
regard the description of a material nature and separate 
existence to cold. 
Cold permeates the silver cup or gold, 
With water filled, held brimming in the hand, 
And dew-like moisture gathers on without. 
Thus naught in nature solid seems to be. 
Book I p. 53. 
The doctrine of the indestructibility of matter has 
been commonly accredited to Lavoisier but a recent writ- 
er has shown that the saying attributed to him ‘‘/zen 
ne se perd et rien ne se crée’”’ does not occur in his works 
and that at best he tacitly assumed this which had long 
been believed by others. Kahlbaum traces it to P. 
Mersenne the friend of Descartes but, it iseasy togo many 
centuries back of this and to find the doctrine clearly 
stated in Lucretius. He writes of his atoms: 
Nature reserving these as seeds of things, 
Permits in them no minish nor decay; 
They can’t be fewer and they can’t be less. 
Book 1 p. 57. 
