Popular Science Monthly 



875 



have no little trouble in trying to match 

 colors, whether silks or house paints; not 

 because the chemist cannot make the same 

 shade twice. Indeed the synthesis of dyes 

 is like the multiplication table for reli- 

 ability. It always gives the same result. 



The Modern Chemist Experi- 

 ments on Paper 



Instead of messing around in 

 a laboratory with a dozen or 

 more retorts, a lot of stains and 

 a dirty, smudg>' atmosphere, 

 the chemist of today simply 

 sits at his desk, far away from 

 the choking acid fumes 

 of his laboratory, and 

 figures out on a sheet 

 of paper the colors he 

 wishes to produce. He 

 knows that certain in- 

 gredients will yield 

 certain results and pro- 

 ceeds to combine them 

 in such a way as to 

 build up what he wants 

 before he ever carries 

 out the actual chemi- 

 cal reactions theoreti- 

 cally worked out. 



Such a procedure 

 forms a remarkable 

 contrast with the 

 laborious experi- 

 menting which led 

 to the discovery 

 of mauve, the first 

 coal tar dye, by 

 Perkin, in 1856. 

 He was an en- 

 thusiastic young 

 English chemist 

 who took a notion 



to build up quinine from simpler chemicals. 

 He chose a college Easter vacation for his 

 research work and labored day and night 

 to obtain his ends. But quinine did not 

 result; only a dingy dark precipitate was 

 formed. Perkin was disgusted. The stuff 

 would not even dissolve in water. He 

 tried alcohol. To his astonishment and 

 delight, a most beautiful violet color was 

 produced which dyed silk a magnificent 

 purple. 



Though only eighteen years of age, 

 Perkin was old enough to realize the vast 

 commercial possibilities of this discovery. 

 Within three years the women of England 

 had lost all sense of reason over the new 



cok 



Punch made the following comment : 



"Lovely woman is just now afflicted with a 

 malady- which apparently is spreading to so serious 

 an extent that it is high time to consider by what 

 means it may be checked. . . . One of the first 

 symptoms by which the malady declares itself 

 consists in the eruption of a measly rash of ribbons 

 about the head and neck of the person who has 



caught it. The erup- 



Hair fastened with glue 

 from all day suckers 



Cheek colored wHh 

 poisonous dye from candy 



Waist dyedv/rth coloring 

 matter from lollypops 



tion, which is of a 

 mauve color, soon 

 spreads, until, in 

 many cases, the suf- 

 ferer becomes com- 

 pletely covered with 

 it." 



5kirt dyed another^ 

 color also from 

 ollypops 



A poisonous 

 lollypop 



Dyed vivid 

 areen from a 

 cenrs worth of 

 lollypops 



^Plated -j 

 ■'with copper' \^ 

 from can of peas 



Professor D. R. Hodgdon dyed this doll's brightly- 

 colored clothes with coal tar coloring-matter 

 which he obtained from cheap, poisonous candy 



In speaking of 

 finished dyes, we 

 ha\e jumped 

 from coal clean 

 over the thou- 

 sand and one in- 

 tervening pro- 

 cesses, to the 

 usable product. 

 After coal is first 

 split up, the next 

 most important 

 way station on 

 our trip from coal 

 to the outskirts 

 of the whole in- 

 dustn,, is coal 

 tar. 



Coal tar is the 

 most disagree- 

 able, foul-smell- 

 ing, black sticky 

 liquid you ever 

 saw. 



When gas is 

 distilled coal tar 

 condenses in the 

 pipes. For years 

 e\'ery gas works 

 had to contend with it as an extremely 

 bothersome by-product. It was worse than 

 waste, for vegetation died wherever it was 

 spilled; streams were polluted if it was 

 allowed to drain into them. It is a com- 

 bination of liquid and solid substances 

 consisting mainly of hydrocarbons, which 

 are complex compounds of hydrogen and 

 carbon. The separation of these constitu- 

 ents into such products as paraffin, naph- 

 tha, benzene, cyanogen and the like, is 

 now an industry netting millions of dollars 

 annually. Coal tar is now practically dis- 

 tilled in order to obtain these products. 



Fractional distillation is the gradual rais- 

 ing of the temperature, driving off the 



«5hoe lined with 

 shellac from peach pits 



