10 Sketch of the Improvements in Scierice [Jan. 



of it ; but it is not necessary to dwell upon the subject, as the 

 whole depends upon a well-known electrical law, that when a sub- 

 stance is brought near an excited body the electricity of the nearest 

 side is different from, but that of the remotest side similar to, that 

 of the excited body. All the attractions and repulsions so familiar 

 to electricians depend upon this well-known law. 



VII. Magnetism. 



°^ Magnetism has made very little progress for a considerable series 

 years. Hence we have no reason to be surprised that little has 

 been added to our knowledge of the subject during 1813. 



The magnet is liable to two kinds of variation, the annual and 

 the diurnal. We possess very few good observations on the diurnal 

 variation, and therefore have not suflicient data for investigating its 

 cause. On that account the observations of Col. Beaufoy, which 

 have been regularly published in the Annals of Philosophy, and 

 which have been made with a better apparatus than any preceding 

 observations, and with every possible attention to accuracy, possess 

 peculiar value, and will probably throw a new light on this obscure 

 subject. It would be premature to attempt to draw any deduction 

 from these experiments till they have been continued for a year. A 

 very slight examination of them, comjjaring them with the diary of 

 the weather, vvill satisfy us that heat alone is not sufficient, as Mr. 

 Canton supposed, to account for these diurnal variations. 



VIII. Chemistry. 



This is the science which has made by far the greatest progress 

 duiiiig the course of the year. It will consequently occupy a 

 greater space than any of the preceding. It vvill be attended with 

 some advantage to subdivide it into its various departments. This 

 will enable us to judge what part of it at present engages the prin- 

 cipal attention of chemical philosophers. 



1. Heat. 



Considerable additions have been made lately to tlie precision of 

 our kiiowlediie of some important pltenomcna connected with heat 

 and combustion. The newly discovered facts have overturned some 

 of our most ingenious and plausible theories, and have shown us 

 that the pliiloso})hy of heat and combustion is not so far advanced 

 as had been conceived. 



1. Count Kumford, who has devoted himself fo the experimental 

 investigation of heat with much perseverance and success, iias lately 

 ascertained how much heat is given out by various bodies during 

 coml)ustion. The following table exhibits the quantity of water 

 that would l)e raised fiom the freezing to the boiling point by the 

 combustion of a jiound troy of the respective substances : — 



