Dr. Andrews's Report on the Heat of Combination* 525 



Temperature of air ^,^5,„^ .fej,» \l 2'S 1 2-8 



Increments observed 1*19 ri9 



Heat for 1 grm. BaO, Co O3 . . 22-1 \o ifumvMhxSV 



Heat for 1 equiv. BaO, C^ O3. . 309-0 



Acetate of Lead a7id Sulphuric Acid. — Of the acetate 30"8 grms. 

 taken and an equivalent of the acid.'' (•.''''" 



. o? - o 



Temperature of air \ 14'9 14<"1 



Increments observed 2'8-l' 2-86 



Heat for 1 grm. PbO, SO3 28*0 29*2 



Heat for 1 equiv. PbO, SO3 . . 54.2-0 



Nitrate of Lead and Sulphuric Acid. — Of nitrate of lead 26-26 

 gjrms. taken. 



(Mjir, ^-Temperature of air 9*8 10*3 



Increments observed 1*63 1-66 



'mIi . .iHeat for 1 grm. PbO, SO3 16-3 16-4 



■ ■ Heat for 1 equiv. PbO, SO3 . . 309'8 



Acetate of Lsad and Oxalic Acid. — 15-4 grms. of acetate of lead 



were taken. '^ *'"^^* '" "'' 



. !, .. ■ f* .'. o 



{^^ Temperature of air 9-8 



Increment observed 2-12 



Heat for 1 grm. PbO, C2 O, 4.-3 



Heat for 1 equiv. PbO, €3 O3 792'9 



aJ. These experiments can only be regarded as introductory to an 

 extended and interesting subject of inquiry. With such limited data, 

 it would be premature to attempt to draw any general inferences. 



Solution of Metals in Nitric Acid. — Every chemist is familiar 

 with the violent action of nitric acid on zinc and copper, and the 

 abundant evolution of gas which accompanies it. But the facility 

 with which the gases may be condensed by the acid solution is 

 probably not so generally known, and when the experiment is made 

 for the first time cannot fail to excite surprise. If a small vessel of 

 thin German glass, of about the capacity of half a fluid ounce, be 

 half-filled with nitric acid of density 1-4, and a slip of zinc be sus- 

 pended in the upper part so as not to touch the acid, the flask her- 

 metically sealed, and finally inverted while surrounded with cold 

 water, a very violent action will occur, but without bursting the ves- 

 sel. Having ascertained these facts, there was little difficulty in 

 measuring the heat disengaged during the solution of the metals in 

 nitric acid. The metal was weighed in a glass tube open at one end, 

 which was introduced into a thin glass vessel containing nitric acid 

 of specific gravity 1-4. The latter was then carefully closed and 

 introduced into a copper vessel filled with water, and suspended in a 

 metallic cylinder which was capable of rotation. On inverting the 

 apparatus, the metal and acid came into contact, and the solution 

 was completed in a few seconds. The rotation was afterwards con- 

 tinued for five minutes, which was sufficient to diffuse the heat dis- 

 engaged through every part of the calorimeter.a'i^ ^ii'C i-Ci. \i.'.VnvA>. 



