188 M. Bemtius on the Combinations of [Sept. 



very considerable amount may exist between the calorific pro- 

 perties of light produced from sources of a different description, 

 in comparison with their illuminating intensities. In this point 

 of view, therefore, I cannot feel the force of the above reason- 

 ing; but further, by means of Leslie's Photometer, we can easily 

 and decisively ascertain what is the amount of the heating power 

 belonging to the light of incandescent metal, as distinct from all 

 other heating influences which mightbe supposedto accompany it. 

 This is an experiment which, as before remarked, I have re- 

 peatedly tried with iron raised to the highest point of bright- 

 ness which a common tire could communicate. After observ- 

 ing and allowing for the effect of adventitious light, I was 

 somewhat surprised at the magnitude of the effect displayed 

 by the very weakly illuminating rays proceeding from the hot 

 iron. In 30 seconds the rise observed, in several different 

 repetitions, was from 10 to 13 degrees. The bulb was coated 

 with Indian ink, and enclosed in the glass case. 



To guard against the possibility of any simple heat affecting 

 the bulb, which, in the short time of observation, might not be 

 counterbalanced by radiation ; the precaution of interposing a 

 screen of piate glass about half way between the instrument 

 and the iron was adopted. The whole distance was nearly 

 eight inches. The iron, a cylindrical mass about six inches 

 long and 1*5 diameter, suspended vertically, the bulb of the 

 photometer opposite its middle point. At subsequent stages 

 of the cooling process, till the mass of iron became quite dull, 

 proportional effects were displayed by presenting the instru- 

 ment to its light at successive intervals during a space of Ave 

 minutes or more. These results form part of a set of. experi- 

 ments hereafter to be detailed, in which more numerous in- 

 stances of this and other kindred phenomena will appear. 



Article VL 



On the Combinations of Acetic Acid with Peroxide of Copper, 



By Jac. Berzelius.* 



A knowledge of the nature of salts containing an excess 

 of base, and of the ratios in which different quantities of the 

 same base combine with a determinate quantity of an acid, is 

 of the utmost importance for a complete and unexceptionable 

 exposition of the laws of chemical proportions. In some earlier 

 memoirs, I have attempted to develope the proportions by which 

 the quantity of base augments in sub-salts, and I have attempted 

 on the same occasions to demonstrate that, at least in all the 



* From Kongl. Vet. Acad. Handl. 1823, St. II. 



