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CHEMICAL SCIENCE. 



CHEMICAL COMBINATIONS. 



DR. T. WOOD, at the British Association stated, in a paper on the 

 above subject, that he conceived that there was a mutual dependence 

 or relation between the space and the matter which compose a body, 

 such relation causing the distance between the particles to be definite ; 

 that, therefore, if the nature of the matter changes, the distance 

 between its particles must also change ; that, if two bodies be mixed 

 or brought together, at insensible distances, as in solution, they are no 

 longer two but one body, and, as they were dissimilar previously 

 to being mixed, the one body they form must be dissimilar from either 

 separately, and so the distance between the particles must be different. 

 It must also be less ; for, if greater, the bodies could be brought 

 nearer at sensible than insensible distances, and so could not form one 

 body at all, which is contrary to our supposition. But, as every molec- 

 ular movement is accompanied by its opposite, this lessening of dis- 

 tance between combining particles is attended with expansion among 

 others, and this expansion is the heat. 



MOLECULAR PECULIARITIES OF CERTAIN BODIES. 



DR. TYNDALL, at the British Association, Belfast, stated, that 

 drawn by former researches to the contemplation of molecular action, 

 he had commenced a series of inquiries on this subject, the first 

 fruits of which were here laid before the meeting. Organic substan- 

 ces naturally suggest themselves as likely to afford instructive exam- 

 ples of molecular action ; for here nature, to attain her especial ends, 

 has arranged her materials in a peculiar manner, which arrangement 

 makes itself manifest when the substance is made the vehicle of a 

 force. Wood was first examined ; cubes were cut from a number of 

 trees, four faces of each cube being parallel to the fibre, and conse- 

 quently two perpendicular to it. Further, two opposite faces were par- 

 allel to the ligneous layers and two perpendicular to them. The problem 

 to which Dr. Tyndalf addressed himself was as follows : If a source of 

 heat of definite measurable amount be brought close up to the face of the 

 cube required the quantity transmitted through the mass of the cube to 



