DYEING. 



219 



Substantive 

 Colouring 

 Matters. 



Experi 



its of 

 Jussieu and 

 Ileaumur. 



discovered the colouring matter placed in a " white 

 vein lying transversely in a little furrow or cleft next 

 to the head of the fish, which," says he, " must be dig- 

 ged out with the stiff point of a horse hair pencil, made 

 short and tapering, by reason of the viscous clamminess 

 of the white liquor in the vein, that so by its stiffness 

 it may drive in the matter into the fine linen or white 

 silk" intended to be marked. Letters or marks made 

 in this way, with the white liquor in question, " will 

 presently," adds he, " appear of a pleasant green colour, 

 and if placed in the sun, will change into the following 

 colours, i. e. if in the winter, about noon, if in the sum- 

 mer, an hour or two after sunrise, and so much before 

 setting, ( for in the heat of the day in summer, the co- 

 lon rs will come on so fast that the succession of each 

 colour will scarce be distinguishable ;) next to the first 

 light green will appear a deep green, and in a few mi- 

 nutes this will change into a full sea-green, after which 

 in a few minutes more, it will alter into a watchet blue, 

 and from that, in a little time more, it will be of a pur- 

 plish red, after which, lying an hour or two, (supposing 

 the sun still shining) it will be of a very deep purple 

 red, beyond which the sun can do no more." He re- 

 marks, however, that " these changes are made faster or 

 slower, according to the degree of the sun's heat ;" " but 

 then," adds he, " the last and most beautiful colour, af- 

 ter washing in scalding water and soap, will (the mat- 

 ter being again exposed to the sun or wind to dry) be 

 much a differing colour from all those mentioned, i. e. 

 a fair bright crimson, or near to the Prince's colour, 

 which, afterwards, notwithstanding there is no styptic 

 to bind the colour, will continue the same, if well or- 

 dered, as 1 have found in handkerchiefs that have been 

 washed more than forty times, only it will be some- 

 what alloyed from what it was after the first washing." 

 60. M. Cole sent some of the linen marked in this 

 way to I)r Plot, then one of the secretaries of the 

 Royal Society, in November 1684; which was soon af- 

 ter shewn to Charles the Second, who admired it great- 

 ly, and dc.-iml that some of the liquor might be sent 

 to town, in order that he might witness its effects. But 

 before tliis could be done, the king died, and it appears 

 that little further interest was at that time excited 

 about the matter. After an interval of twenty-four 

 years, M. Jussie... found a small species of buccinum 

 on the western shores of France, and presented some 

 of them in 1709 to the Royal Academy of Sciences at 

 Paris j and in the following year, Reaumur discovered 

 great numbers of the same shell-fish on the co;i-t of 

 Poitou. Reaumur observed, that the stones and little 

 sandy ridges round which they had collected, were co- 

 vered with a kind of oval " graines," some of which 

 were white, and others of a yellowish colour ; and ha- 

 ving squeezed some of them upon the sleeve of his 

 .shirt, he was agreeably surprised, in about half an hour, 

 to find it stained of a fine purple colour, which he 

 .is unable to discharge by washing. He next collect- 

 ed a quantity of these grains, and carrying them to 

 his apartment, bruised and squeezed different parcels 

 of them upon bits of linen ; but, to his great surprise, 

 after waiting two or three hours, no colour appeared 

 ii|.n the spots wetted with the liquor. L'nable to con- 

 ceive the reason of this disappointment, and having al- 

 most determined to return again to the sea-shore, and 

 repeat the experiment on the same plan as before, he 

 cli.-inced to perceive some purple spots, occasioned by 

 drops of the liquor which had accidentally fallen upon 



a part of the plaster of Paris with which the sides of Substantive 

 the window were covered, and which having been more Colouring 

 strongly acted upon by the light than the bits of linen 

 wetted with the same liquor in the interior part of the 

 room, had become purple, though the day was then 

 cloudy. He afterwards made a variety of experiments 

 with the liquor of the buccinum ; but as he was, from 

 the outset, impressed with the notion that the conver- 

 sion of it to purple was occasioned by some mechanical 

 action of the air, he never discovered the true cause of 

 the production of that colour. 



61. Reaumur conceived the grains in question to be Proposal of 

 the eggs or spawn of some fish, but whether of the bucci- ^ r g * ^"" 

 num or any other species, he was uncertain, and under purpuraanJ 

 this uncertainty he proposed calling them ceitjs de pour- buccinum 

 pre, eggs of purple. The colour which they produced in topical 

 was at least equal, if not superior, in beauty, as well as dyeing. 

 durability, to that ot the buccinum ; though the colour- 

 ing matter of the latter WAS much thicker, and passed 



less quickly through the different shades of colour, on 

 exposure to the light of the sun. He also found that 

 the liquor of the buccinum tasted as hot as the hottest 

 pepper, whilst that of the purple eggs was saltish. But 

 even the latter was so viscid, that, when topically ap- 

 plied to linen, it did not run ; and as die grains were, 

 according to his accounts, so plentiful, that one man 

 might collect hah 1 ' a bushel of them in a few hours, 

 there is certainly reason to conclude, says Dr Bancroft, 

 that they would be highly useful, at least in calico- 

 printing, where their liquor might be applied with the 

 greatest facility, both for penciling and printing, as a 

 substantive topical colour, and where a small quantity 

 would go far, especially upon fine muslins 



62. About the beginning of the year 1 7.^(1, Duhamel Experi- 

 discovered the purptira in great abundance upon the nients of 

 coast of Provence. He found the viscid colouring mat- Duhamel. 

 ter of the fish to be white, except in a few instances in 



which it was green, an appearance which he ascribed 

 to disease. The white liquor being exposed to the sun's 

 rays, assumed the following colours : 1. A pale yellowish 

 green; 2. An emerald green ; 3. A dark blueish green ; 

 4. A blue with a tinge of red ; 5. A purple ; and these 

 changes all happened in less than five minutes. In all 

 the experiments which were made with the purpura, 

 the presence of light was found essential to the forma- 

 tion of the purple colour ; and the effect was produced 

 most expeditiously when the influence of the sun's rays 

 was most powerful. 



63. Little doubt can now be entertained of the identity The shell 

 of the shell fish employed by the ancients, and those dis- fi '' "^ uy 

 covered by Cole, Reaumur, and Duhamel. Both Ari- ^moderns, 

 stotle and Pliny have informed us, that the liquor of the Jj^'om." 

 purpura was white ; and the latter also remarks, that plovl in 

 the purple colour which it afforded was not instanta- dyeing the 

 neously produced, but after a succession of several co- Tyrian pur- 

 lours, of which green* was one. We have also a de- l' !e . b .v tlltt 

 scription of the manner of catching the shell fish, em- ' ul 

 ployed for the purple dye, written by an eye w itness, 

 Eudocia Macrembolitissa, daughter of the emperor 

 Con.stantine the Eighth, who lived in the eleventh cen- 

 tury, while the knowledge of dyeing the Tyrian purple 



still remained : and from which it appears, that the 

 ancient purple did not acquire its due lustre and per- 

 fection until it had been exposed to the sun's rays. 



64. Berthollet is inclined to believe, that the changes, Cause of the 

 which the liquor of the purpura and buccinum under- clllln gc ot 

 goes by exposure to the sun's rays, are owing to the 



Color avstcrtn m G'toicco, et ircucenti similii mari. Lib. ix. cap. 36. 



