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SCIENCE. 



[N. S. Vol. XVI. No. 405. 



ing- men from the very earliest dawn of 

 speculation upon the external world; but 

 it will suffice for the present purpose if, 

 disregarding ancient philosophers and even 

 medieval alchemists, we take up the sub- 

 ject where it stood after the great revival 

 of learning, and as it was regarded by the 

 father of the inductive method. That this 

 was an especially attractive subject to 

 Bacon is evident from the frequency with 

 which he recurs to it in his different works, 

 always with lamentation over the inade- 

 quacy of the means at disposal for obtain- 

 ing a considerable degree of cold. Thus 

 in the chapter in the 'Natural History,' 

 'Sylva Sylvarum,' entitled 'Experiments 

 in consort touching the production of cold, ' 

 he says, ' The production of cold is a thing 

 very worthy of the inquisition both for the 

 use and the disclosure of causes. For heat 

 and cold are nature's two hands whereby 

 she chiefly worketh, and heat we have in 

 readiness in respect of the fire, but for cold 

 we must stay till it cometh or seek it in 

 deep caves or high mountains, and when 

 all is done we cannot obtain it in any de- 

 gree, for furnaces of fire are far hotter 

 than a summer sun, but vaults and hills 

 are not much colder than a winter's frost.' 

 The great Robert Boyle was the first ex- 

 perimentalist who followed up Bacon's 

 suggestion. In 1682 Boyle read a paper 

 to the Royal Society on 'New Experiments 

 and Observations touching Cold, or an 

 Experimental History of Cold,' published 

 two years later in a separate work. This 

 is really a most complete history of every- 

 thing known about cold up to that date, 

 but its great merit is the inclusion of 

 numerous experiments made by Boyle 

 himself on frigorific mixtures, and the gen- 

 eral effects of such upon matter. The 

 agency chiefly used by Boyle in the con- 

 duct of his experiments was the glaciating 

 mixture of snow or ice and salt. In the 

 course of his experiment he made many 



important observations. Thus he observed 

 that the salts which did not help the snow 

 or ice to dissolve faster gave no effective 

 freezing. He showed that water in be- 

 coming ice expands by about one ninth of 

 its vohime, and bursts gun-barrels. He 

 attempted to counteract the expansion and 

 prevent freezing by completely filling a 

 strong iron ball with water before cooling; 

 anticipating that it might burst the bottle 

 by the stupendous forces of expansion, or 

 that if it did not, then the ice produced 

 might under the circumstances be heavier 

 than water. He speculated in an ingenious 

 way on the change of water into ice. Thus 

 he says, ' If cold be but a privation of heat 

 through the recess of that ethereal substance 

 wliich agitated the little eel-like particles 

 of the water and thei-eby made them com- 

 pose a fluid body, it may easily be con- 

 ceived that they should remain rigid in the 

 postiires in which the ethereal substances 

 quitted them, and thereby compose an un- 

 fluid body like ice ; yet how these little eels 

 should by that recess acquire as strong an 

 endeavor outwards as if they were so many 

 little springs and expand themselves with 

 so stupendous a force, is that which does 

 not so readily appear.' The greatest de- 

 gree of adventitious cold Boyle was able to 

 produce did not make air exposed to its 

 action lose a full tenth of its own volume, 

 so that, in his own words, the cold does not 

 'weaken the spring by anything near so 

 considerable as one would expect.' After 

 making this remarkable observation and 

 commenting upon its unexpected nature, 

 it is strange Boyle did not follow it vip. 

 He questions the existence of a body of 

 its own nature supremely cold, by partici- 

 pating in which all other bodies obtain that 

 quality, although the doctrine of a primum 

 frigidum had been accepted by many sects 

 of philosophers; for, as he says, 'if a body 

 being cold signify no more than its not 

 having its sensible parts so miich agitated 



