Geology and Natural History. 63 



(11.) The quantities of heat evolved in the nactioTi of om- niole- 

 ile of sodic hydrate with one molecule of ;u-i<l-iiyilrato in .uiuc'- 

 is solution are very different. Fluohydric acid o-ives tli(> uieat- 

 ,t amount of heat (163 . .); then comes sulpl.urous acid (I5l> . .), 

 ypophosphorous acid (152 . .), arsenic acid (lot) . .); the different 

 iiosphoric acids, phosphorous, selenious, selenic and sulphuric 

 .•i<ls give between 148 . . and 144 . . The evolution of heat is less 

 1 tliocases of the hydrogen acids of chlorine, bromine and iodine 

 lid nitric acid (i;37..) ; much less in the cases of boric and car- 

 onic acids (110. . to 111 ..) while sulphydric, silicic and cyaiihy- 

 ric acids give the smallest amounts of heat. If however \x e 

 tion of heat which a molecule of sodic hydrate 

 quantity of acid necessary to foini a uortiial 

 salt, the order of the series is somewhat different, but here alsc 

 flxiohydric acid occurs with the greatest quantity of heat (103 . .) ; 

 then follow sulphuric, selenic and hypoj)hosp]iorous acide (155 . . to 

 152..), then sulphurous, hyposulphuric, phosphorous and oxalic 

 acids (145 , . to 141 . .), and so we pass gradually down to sulphy- 

 dric, cyanhydric and silicic acids. 



'" ' " lome of the acids which I have studied the heat of 

 1 had been deteiTnined already. The older investiga- 

 tions often show material differences from the numbers determined 

 by me. The determinations of Favre and Silbermann in particu- 

 lar differ greatly. The results of these investigators for chlor-, 

 brom- and iodhydric acids and for nitric and j.hosphoric achis are 

 from 10 to 12 per cent too high, for instance for the tiist four acids 

 151 . . to 152 . . instead of laV . . . The cause very pr(il)al>ly lies in 

 the inaccurate indications of the mercurial calorimeter employed 

 by them, and I doubt very much whether the experiments recently 

 made with the same apparatus possess a greater accuracy. I have 

 already found several material errors in the published 'results to 

 which I shall return hereafter. For the rest I refer, with reference 

 to the inaccuracy of the results obtained with mercury, to my 

 ""mmunication in the Reports of the German Chemical Society at 



teSrali^ 



Berlin, 1869, 



11. Geology and Natueal History. 



1. N'otes on the American Mastodon and other fossils; by Dr. J. 

 Leidy (Proc. Acad. Nat. Sci. Philad., Sept. 1870).— Dr. Leidy, after 

 brief notes on the specimens of Mastodon in Boston and Cam- 

 bridge, makes the following observations on some bones in the 

 Museum of Amherst College. 



Prof. Shepard has recently collected together many interesting 

 fossil remains of vertebrates. Among these are a multitude of 

 specimens obtained by his son from St. Helena Island, and the 

 famous Ashley River deposits of South Carolina. Those from the 

 latter locality consist mainly of Zenglodons, Cetaceans and 

 Fishes, but also include remains of Mastodon, the Elephant, and of 

 Equus Major and B. fraternus. The St. Helena Island fossils 

 consist of bones, fragments of jaws and teeth of the Mastodon. 



