FAMILIAR LETTERS ON CHEMISTRY. 



combination with oxygen, to which they are united in one, two, or more definite 

 and unalterable proportions, forming compounds which are termed metallic oxides, 

 and these again, combined with oxides of other bodies, essentially different to 

 metals, namely, carbon, and silicium. If to these we add certain compounds of 

 sulphur with metals, in which the sulphur takes the place of oxygen, and forms 

 sulphurets, and one other body common salt (which is a compound of sodium 

 and chlorine,) we have every substance which exists in a solid form upon our globe 

 in any very considerable mass. Other compounds, innumerably various, are found 

 only in small scattered quantities. 



The chemist, however, did not remain satisfied with the separation of minerals 

 into their component elements, i. e., their analysis ; but he sought by synthesis 

 (i. e., by combining the separate elements and forming substances similar to those 

 constructed by nature), to prove the accuracy of his processes and the correctness 

 of his conclusions. Thus he formed, for instance, pumice-stone, feld-spar, mica, 

 iron pyrites, &c., artificially. 



But of all the achievements of inorganic chemistry the artificial formation of 

 lapis lazuli was the most brilliant and the most conclusive. This mineral, as 

 presented to us by nature, is calculated powerfully to arrest our attention by its 

 beautiful azure-blue color, its remaining unchanged by exposure to air or to fire, 

 and furnishing us with a most valuable pigment, Ultramarine, more precious than 

 gold ! 



The analysis of lapis lazuli represented it to be composed of silica, alumina, 

 and soda, three colorless bodies, with sulphur and a trace of iron. Nothing could 

 be discovered in it of the nature of a pigment, nothing to which its blue color could 

 be referred, the cause of which was searched for in vain. It might therefore have 

 been supposed that the analyst was here altogether at fault, and that at any rate 

 its artificial production must be impossible. Nevertheless, this has been accom- 

 plished, and simply by combining in the proper proportions, as determined by 

 analysis, silica, alumina, soda, iron, and sulphur. Thousands of pounds weight are 

 now manufactured from these ingredients, and this artificial ultramarine is as 

 beautiful as the natural, while for the price of a single ounce of the latter we 

 may obtain many pounds of the former. 



With the production of artificial lapis lazuli, the formation of mineral bodies 

 by synthesis ceased to be a scientific problem to the chemist ; he has no longer 

 sufficient interest in it to pursue the subject. He may now be satisfied that ana- 

 lysis will reveal to him the true constitution of minerals. But to the mineralogist 

 and geologist it is still in a great measure an unexplored field, offering inquiries 

 of the highest interest and importance to their pursuits. 



After becoming acquainted with the constituent elements of all the substances 

 within our reach, and the mutual relations of these elements, the remarkable 

 transmutations to which bodies are subject under the influence of the vital powers 

 of plants and animals, became the principal object of chemical investigations, and 

 the highest point of interest. A new science, inexhaustible as life itself, is here 

 presented us, standing upon the sound and solid foundation of a well established 

 inorganic chemistry. Thus the progress of science is, like the development of 

 nature's works, gradual and expansive. After the buds and branches spring forth 

 the leaves and blossoms, after the blossoms the fruit. 



Chemistry, in its application to animals and vegetables, endeavors jointly with 

 physiology to enlighten us respecting the mysterious processes and sources of 

 organic life. 



LETTER II. 



MY DEAR SIR : 



In my former letter I reminded you that three of the supposed elements of 

 the ancients represent the forms or state in which all the ponderable matter of our 

 globe exists ; I would now observe, that no substance possesses absolutely any one 

 of those conditions ; that modern chemistry recognises nothing unchangeably solid, 

 liquid, or aeriform : means have been devised for effecting a change of state in 

 almost every known substance. Platinum, alumina, and rock crystal, it is true, 

 cannot be liquefied by the most intense heat of our furnaces, but they melt like 



