Chemistry and Physics. 411 



He thus finds some lime (1'62 to 2-17 per cent.) not combined with 

 the acids detected. This is accounted for by the existence of fluorine 

 in bones, with which this lime is probably united. According to the 

 analyses of Berzelius, the bone of a human thigh contained 3 percent, 

 of fluorid of calcium, and a bone of an ox 4*25 per cent out of those 

 portions which resisted the action of heat. Marchand has found in hu- 

 man bones one per cent, of this fluorid, or 16 per cent, in the bones 

 when calcined. Heintz, in his experiments, found 2*05 per cent., cor- 

 responding to 2-97 per cent, in the bones after calcination. The amount 

 of fluorid of calcium corresponding to the lime found in Heimz's analy- 

 ses, equals 3*57 and 3*24 per cent, of the calcined material. 



Heintz has also found that bones after boiling in water contain no 



j trace of iron. He attributes that found by some chemists to the blood 



I which is not easily removed entirely by cold water. 



j 6. On the Specific heat of Potassium, with remarks on the equiva- 



J lents of Silica and the Alkalies; by V. Regnault, (Ann. Chem. Phys. 



1.3], xxvi, 261.) — The author considers the bearing of the law brought 

 out by Dulong and Petit — that the specific heats are in an inverse ratio 

 to the atomic weights — on the equivalents of silver and other elements. 

 He observes that the law holds true for a large part of the elements. 

 Uranium, silver and carbon are three of the exceptions. Uranium has 





not yet been sufficiently investigated. As to silver, the law alluded to 

 gives an equivalent half of that usually adopted, and would make the 

 oxyd Ag 2 o, instead of AgO, and the sulphuret Ag 2 S, instead of AgS. 

 The isomorphism of Cu 2 S with the sulphuret of silver, the analogy of 

 chloric! of copper and chlorid of silver, besides other reasons, are urged 

 as favoring a change in the equivalent. 



Carbon exists in three conditions, each with distinct specific heats ; 

 an d it is important to ascertain which of these is its condition in its 

 combinations. It is natural to assume that to be the modification in which 

 carbon is most disaggregated. But the capacity for heat of carbon, as 

 found by Regnault, from the decomposition of organic substances, cor- 

 responds to the equivalent 150, instead of 75 the number usually 

 adopted. As an important proof on this point, the author mentions 

 jhat among a great number of organic compounds whose composition 

 is well determined, the number of the equivalents of carbon is an even 

 number. There are two exceptions to this, viz., in the oxyd of carbon 

 (CO), and carbonic acid (CO 2 ). But there is no special reason for 

 filing CO rather than C 2 O 2 ; and chemists write the formula of car- 

 bonic acid CO 2 , because they regard as neutral salts, those of most 

 common occurrence, — the carbonates of lime, of baryta, &C-, and as 

 ^'carbonates, the alkaline carbonates which contain double the quantity 

 °f carbonic acid. The anomaly disappears if we adopt the above view 

 and regard the latter as neutral carbonates (as some chemists have ac- 

 tually done), in which case the others are basic carbonates. 



The same law as regards the inverse relation of specific heat and 



atomic weight holds also for compounds. Regnault suggests farther 

 that the alkaline oxyds should have the form R 2 0, and the equivalent 

 be halved. Soda and oxyd of silver, or sulphate of soda and sulphate 

 °f oxyd of silver, have been known to be isomorphous; and this change 

 w ould render the composition analogous. With reference to this point, 



