﻿ATOMIC HEAT TO CRYSTALLINE FORM. 



115 



very elevated temperature. Tellurium associates itself with this class by heat and 

 volume, as well as by chemical properties. Reasons exist for ranking oxygen with 

 these three elements. The probability of such a connection finds some support in the 

 fact that the combining measure of aqueous vapor and sulphuretted hydrogen is two 

 volumes, and that of the 'oxide, sulphuret and telluret of ethyl, four volumes. An 

 atom of each of the two former substances, probably possesses a heat-sphere of the 

 same size. The calorific envelopes of the atoms of the last three are also equal to 

 each other in extent, but twice as great as those of the former. The relation of the 

 oxides and sulphurets is seen in the subjoined table. 



Oxides. 



Atomic 

 Heat. 



Atomic | 

 Volume. 



i 



Sulphides. 



Atomic 

 Heat. 



Atomic 

 Volume. 



HgO 



5.665827 



9.855 



HgS 



6.00736 



14.625 



MnO 



5.58956 



7.568 



FeS 



5.97080 





CuO 



5.65199 



6.297 



NiS 



5.84273 





NiO 



5.97276 





CoS 



5.70548 





MgO 



5.71320 



6.500 



ZnS 



5.93005 



12.286 



ZnO 



5.98176 



7.178 



PbS 



6.09303 



16.592 



PbO 



5.72192 



11.982 



SnS 



6.27375 



... 



CaO 



5.10150 



9.016 









SnO 



6.2980 



10.044 









Sulphuric and manganic acids are isomorphous. From this is inferred the iso- 

 morphism of the elements sulphur and manganese. Hence manganese is regarded as 

 the connecting link between the first three elements in the table, called the sulphur 

 class by Graham, and the next seven, named the magnesian class. Manganese is 

 regarded, therefore, as a sort of transition element, by which one group runs into or 

 is blended with the other, — a good example of the artificiality or unreality of scientific 

 classification in general. For the great plan of nature is, in the main, so uniform, 

 that the gaps which apparently dissociate the different parts are being constantly 

 filled up as new discoveries are made. Now, manganese has an atomic heat of 4.0059, 

 and an atomic volume of 3.466. The first connects it, therefore, with both groups, 

 and the last with the magnesian series. The mean atomic volume of most of the 

 bodies in the second class, is a multiple by three of that of the first ; the others bear 

 an equally simple relation. The correspondence of their elements in heat and volume, 

 is of itself sufficient to bring these two classes into one category. Moreover, their 

 more perfectly isomorphous protoxides evince a similar relationship in heat and 

 volume, as shown in the second table. It may be interesting to observe in this con- 

 nection that ice (HO) and protoxide of zinc, (ZnO) which differ not much in atomic 

 heat, have been seen to assume the same regular, six-sided form. Their complete 

 isomorphism, however, has not yet been established by exact measurement. 



At. Heat. At. Volume. 



HO .... 6.480 ... 9.8 



ZnO .... 5.98176 . . . 7.178 



As oxygen, through the resemblance of certain oxides and sulphurets, appears to 



30 



