210 THE POPULAR SCIENCE MONTHLY. 



tiful red body, which he called peonine. Two years afterward, the 

 manufacturers to whom he sold his patents put in the market a sky- 

 blue substance, azuline, which also was a derivative of rosolic acid. 

 The precise nature of rosolic acid has not been determined ; but M. 

 Fresenius has extracted an orange-yellow matter from it, which he 

 calls aurine, and has devised a process for procuring it by heating 

 phenic and sulphuric acids together, and adding oxalic acid six or 

 seven hours afterward. It is not much used now, but is of interest as 

 furnishing in itself blue, red, and yellow. The most important bodies 

 derived from the heavy oils are naphthaline and anthracene, both car- 

 burets of hydrogen, Naphthaline, which is solid at ordinary tem- 

 peratures, and crystallizes with great facility in thin lamellae, is ob- 

 tained simply by leaving the oils in the cold for five or six days, when 

 it becomes solidified. The liquid is decanted off, and the crystals are 

 pressed, to remove the included oil, into thick cakes. Naphthaline is 

 a member of the same series as benzine, and is subject to a similar 

 series of reactions. Reducing its nitrate, Zinin obtained an organic 

 base analogous to aniline, naphthylamine, which is transformed by 

 the loss of hydrogen into rosanaphthylamine. From this is obtained 

 the hydrochlorate of rosanaphthylamine, a body analogous with fuch- 

 sine, of a beautiful rose-color, and easily crystallizable, but of a clearer 

 rose with less of violet than fuchsine. It is dull when applied to 

 wool, but gives very brilliant hues with silk. Dissolved in alcohol, it 

 produces a strange and wonderful effect. The liquid turns bright red, 

 and, under proper presentation to the light, may be seen to be traversed 

 with phosphorescent clouds. If left to stand till the alcohol has slowly 

 evaporated, the bottom of the vessel will be covered with beautiful 

 green, iridescent needles. Naphthaline also furnishes some very com- 

 plex compounds, whence have been derived very yellow dyes, among 

 which Manchester yellow and Martins yellow are the best known. 

 Experiments in substituting molecules of organic radicals for atoms 

 of hydrogen, as has been done with rosaniline, have been made with 

 some success, but the blues thus obtained have not the remarkable 

 fixity and luster of the similar rosaniline products. 



No discovery of coal-tar products is more extraordinary or more 

 fruitful in its bearings than that of the extraction of alizarine, or the 

 artificial ^preparation of the coloring principle of madder, the effect of 

 which has been to work a real economical revolution, and to destroy 

 the most profitable agricultural industry of large districts of country. 

 The madder-root has furnished the most generally used of all dye- 

 stuffs, and the one which constituted the basis of nearly all our colors. 

 The substance to which it owes its peculiar virtues still performs the 

 same functions, but, instead of being derived from the cultivated root, 

 it is now procured by chemical synthesis from stone-coal. 



Alizarine is prepared from anthracene, the second of the more im- 

 portant bodies which we have already spoken of as contained in the 



