26 The Progress of Physical Discovery. JAN. 



apparatus we have already alluded to ; and Mr. Hutton, of Edinburgh, 

 froze the purest spirit of wine. Professor Configliacchi, of Pavia, also 

 froze mercury by the simple evaporation of water. The dilatation of 

 bodies by heat occupied the attention of M. Biot, who, taking for his 

 term of comparison the dilatation of mercury, found that that of other 

 liquids could always be given by the sum of this dilatation of its square, 

 and of its cube, in multiplying each of these three terms, by a particular 

 co-efficient to be determined for such liquids, but which, once determined, 

 remains the same at all degrees. M. Biot calculated the co-efficients for 

 eight liquids ; and it is from him we derive the benefit of the applica- 

 tion of mathematical formula to researches, the excessive nicety of which 

 would otherwise constantly deceive the observer. 



Those accidental combinations, sometimes so fatal to experimentalists, 

 had in this year nearly deprived chemistry of Sir Humphrey Davy, in his 

 researches on the metallization of alkalis and earths ; as well as of Pro- 

 fessor Dulong, of Alfort, whose loss of one of his eyes was remunerated 

 by a brilliant discovery that of a combination of nitrogen with oxymu- 

 riatic acid, which yields an oil that explodes violently when brought 

 into contact with any combustible substance. A new substance was 

 extracted from the brine of the soda of sea- weed, by sulphuric acid and 

 distillation, by a saltpetre manufacturer at Paris, which, among other 

 peculiar properties, has that of rising in a beautiful transparent violet 

 gas. It has undergone long examinations from M. Gay-Lussac and 

 Sir H. Davy, who gave it the name of iodium, which it still retains. 



The raw platina, imported from Peru, besides pure platina, has been 

 found to contain iron, copper, and mercury ; and the four new metals, 

 which the successive researches of Wollaston, Tennant, Descostils, Four- 

 croy, and Vauquelin, have made known to us, under the names of pal- 

 ladium, rhodium, osmium, and iridium ; and the subsequent inquiries 

 of Vauquelin and Langier, in this year, threw additional light upon the 

 nature of the new metals. 



The peace of 1814 added a fresh impulse to the activity of the repub- 

 lic of science. Another series of experiments was made, on both sides 

 of the Channel, on the newly-discovered iodium. M. de Saussure 

 reported to the French Institute the result of his examinations into 

 alcohol and aether ; from whence it appears that in alcohol the watery 

 elements form the third of the whole, and in aether they form the fifth; 

 so that the action of sulphuric acid upon alcohol, to produce aether, would 

 only consist in removing a portion of its water. M. Vauquelin made 

 further researches on the nature of iridium and Osmium ; and Darcet, 

 by his experiments upon bronze, ascertained that it does not harden, 

 like steel, by chill, or immersion in cold water, but obtains its hardness, 

 on the contrary, after having been made red hot, and left to cool slowly 

 in the air. M. Darcet took advantage of this property to construct 

 cymbals, which had hitherto only been made in Turkey, and, as was 

 pretended, by a single workman of Constantinople, who possessed the 

 secret. 



We have alluded to the great chemical system of Lavoisier, which is, 

 however, not entirely perfect, by reason of those acids without oxygen, 

 or hydracids, which appear to form a distinct class. It was, in 1815, 

 ascertained that there yet remained another substance to be added to this 

 class, viz. the prussic acid, which enters into the composition of Prussian 

 blue. The chemical action of the solar light, so well worthy attention 



