42 On the Relation of the Specific [July 



the atom will be f 1*696 H- i = 0-886. Its constituent 

 number will be ^ + i^ = f = 0*625, the square root of 

 which is 0*7905 X *1875=*1482. Therefore i^^ == -1672, 

 the calculated specific heat. Neumann found the specific 

 heat of this substance to be by experiment -1641. 



(3.) The last class of oxides are those which, according 

 to the present views, consist of 2 atoms of oxygen and 1 of 

 base. The principal examples are peroxide of tin, binoxide 

 of manganese, which, by the law of Avogrado, should be 

 formed of 1 atom oxygen and 1 atom base. The calculated 

 specific heat of peroxide of tin is -1134, while the result of 

 experiment was '895 and -965 according to Neumann. 



On the Continent silica is referred to this class. The ap- 

 plication of Avogrado's law, however, shews us that the 

 atomic number and view of the constitution of this sub- 

 stance adopted by Dr. Thomson, is the correct one, viz. 

 that it consists of 1 atom silica -|- 1 oxygen, for 2 being 

 the atomic weight, the half of which is 1, then the consti- 

 tuent number is — - — = 1, the square root of which is 1. 



We have therefore ^i|^ = '1875. Neumann found by 

 experiment the specific heat to be for quartz and rock crystal 

 •1894 and *1883. If we adopt the continental number *9625 

 for the atom of silica, the calculated specific heat is '1948. 



3. Sulphur ets. — The observations of Avogrado and Neu- 

 mann go to prove that the atom of the sulphurets should 

 be divided. Thus for cinnabar the specific heat calculated 

 upon these hypothesis is *511. Neumann found it by ex- 

 periment to be *520; for galena the calculated specific heat 

 is '0501, by experiment *053 and -046 ; for blende the cal- 

 culated number is -1241, experiment -1145; for realgar 

 calculation gives -1117, experiment '1111. These four 

 sulphurets, according to Neumann, afford *757 for the con- 

 stant number which expresses the product of their observed 

 specific heat, multiplied by the weight of the atoms result- 

 ing immediately from the union of an atom of each. Accord- 

 ing to Avogrado, this number is *7484, now the fourth of 

 the latter number is -1871, which differs but slightly from 

 •1875, the half of the co-eflftcient of Dulong and Petit. 

 Avogrado has found that the same law applies to orpiment 

 and bisulphuret of iron. 



4. Chlorides. — The atom of chloride of sodium will require 



