183<X] ' The Progress of Physical Discovery. 23, 



matter, and hence this study, until the time of Fourcroy, had been 

 almost entirely neglected. We have alluded to some of the researches 

 of that illustrious man, which, in 1809, were followed up by Vanquelin, 

 in his analysis of tobacco, in which plant he discovered, among other 

 properties, an animal albuminous matter, and an acrid and volatile 

 principle, different from all yet ascertained in the vegetable kingdom, 

 which gives to it its peculiar qualities, and can be separated by distilla- 

 tion. The juice of the t>elladona, whose effects are so similar to those of 

 tobacco, was found to contain no such principle. In this year, also, the 

 Count Chaptal, whose name will long live in honour for his exertions 

 in the application of the sciences to industry, analysed seven specimens 

 of colours found at Pompeii ; one of which was a deep and rich blue, 

 which Mr. Chaptal showed to be owing to a combination of oxide of 

 copper, lime, and alumine, urging, at the same time, as it was superior 

 to the blue of Cobalt, or any other blue yet known, the necessity of 

 further researches into the method of the ancients. About this time, 

 also, that useful compost, called plaster of Paris, was first brought to 

 perfection. 



The year 1810 produced the admirable treatise of Dessaignes on the 

 Circumstances and Causes of Phosphorescence, which is defined as a 

 durable or fugitive appearance of light, that is not provided sensibly 

 with heat, nor attended with any alteration in unorganized bodies. All 

 its phenomena, according to M. Dessaignes, may be classed under four 

 heads ; viz. Elevation of Temperature Insolation, or Exposure to the 

 Sun Collision and Spontaneous Phosphorescence ; and their several 

 effects are well detailed in his essay. The phosphorescence of the sea 

 he attributes to the presence of phosphoric animalculse emitting a lumi- 

 nous matter, or of the matter itself dissolved in the water ; but there 

 seems still room for investigations into this phenomenon. Berard of 

 Montpelier, about this time, completed the researches of Wollaston and 

 Thomson, on the combination of oxalic acid with different bases ; and 

 Berthollet discovered a process for making artificial muriate of mercury, 

 or calomel, by the intervention of oxygenized muriatic gas. The latter 

 also analyzed sugar and oxalic acid, by reducing them to gas; and 

 Gay-Lussac and Thenard, after analyzation by the same method, framed 

 a rule of division of all vegetable substances into, 1st. Those in which 

 oxygen and hydrogen exist in the same proportions as in water (mz. 

 85 parts of oxygen, and 15 of hydrogen) ; 2d. Those which contain an 

 excess of hydrogen ; and, 3d. Those having an excess of oxygen. 

 Vauquelin analyzed the constituent parts of sugar of the cane, of gum, 

 and of milk, and ascertained that the two latter differed from the former 

 from containing, the first nitrogen, and the second an animal matter ; 

 and Guyton communicated to the French Institute some valuable obser- 

 vations on glass-making, and refuted, to the satisfaction of the minera- 

 logist Dolomien, the notion that the fire of volcanoes acted in a different 

 manner from that of ordinary furnaces. It is now settled that there is 

 no distinction of this nature. 



The Swedish chemist Wilke, as well as Black, had ascertained that 

 evaporation never takes place without the bodies absorbing a large quan- 

 tity of heat, and that all evaporation cools the body from which it ema- 

 nates so much the more in proportion to its quickness ; that the pressure 

 of the atmosphere retards evaporation, and that this change of state 

 never takes place so quickly as in a perfect vacuum. In 1811, Mr. 



