90 ANNUAL OF SCIENTIFIC DISCOVERY. 



to which the piston is pressed downward in the cylinder. Thus a 

 2-inch movement of the piston may be said to give a short flash 

 , and a 6-inch movement to give a long flash . A mechani- 

 cal catch in the cylinder warns the signal-man when he has reached 

 the proper distance for a short or long flash. Engineering. 



THE ANILINE DYES. 



A new red has been obtained by Coupier by a combination of two 

 of the hydro-carbide bases of coal tar, which he has decided to be 

 incapable of yielding a color in their separate condition. It is 

 named toluen red, and is pronounced the richest red yet known. 

 The so-called aniline dyes are among the most beautiful results 

 of chemistry. The series already includes and rivals the colors of 

 the rainbow, and Coupler's analyses promise indefinite varieties 

 of beauty to come. Beginning with the admired varieties of red 

 and purple, such as mauve, magenta, etc., additions like that 

 above named have followed, including the splendid green called 

 verdine, unchanged by candle light, a blue as clear as opal or the 

 Italian sky, a good yellow, and a fair black. Tiie intensity of 

 these colors is shown in the fact that 1 grain of magenta in 1,000,- 

 000 of water gives a good red ; 1 in 10,000,000 a rose-pink ; 1 in 

 20,000,000 gives a blush to the water, and 1 in 50,000,000 a reddish 

 glow. 



Aniline is, however, but a modification of one variety of hydro- 

 carbides constituting the very variable bases of benzine and coal tar, 

 and of which some combination is supposed by the investigator above 

 referred to to be necessary to the production of colors. M. Cou- 

 pier has been engaged in the endeavor to realize industrially the 

 isolation and management of these bases, in order to establish 

 methods for uniform results, with the above instalment of theoret- 

 ical and practical success. The rectified naphtha is resolved into 

 benzole which makes aniline, toluen which makes toluidine,:xylcn 

 and hence xyledine, and a number of other distinct hydrocarbides, 

 the possible compounds of which with each other and with oxy- 

 gen, etc., when fully ascertained, will probably yield a complete 

 and uniform series of dyes, before which the old vegetable and 

 mineral dj'e-stufts will soon disappear. At the meeting of the 

 British Association for 1867, Mr. R. Pullar said: " Orchill or cud- 

 bear will not, I think, be replaced by coal-tar or aniline colors 

 for many purposes, and especially for rich crimson or claret 

 shades on woollen goods. I think there is every likelihood of 

 this material being used to a greater instead of a less extent, and 

 the introduction of the. coal-tar colors has rather increased than 

 diminished its use. I do not think the lichen products will ever 

 compete with the coal-tar colors for light shades. It is a well- 

 known fact, that purples, violets, and other shades produced in 

 former days by the orchill or cudbear, gave way very much sooner 

 than those produced from coal tar. A violet dress or ribbon \\as 

 formerly stained red so easily by exposure to the atmosphere or 

 the slightest acid, that very few persons thought of having such 

 colors ; while, since the introduction of the coal-tar shades, how- 



