PURPLE DYEING, ANCIENT AND MODERN. 401 



If even the chemists were iusufliciently supplied with the raw material, still 

 less could it be procured for the purposes of industry. In Prout's time, the 

 cost of a pound of uretric acid was from thirty-two dollars to forty-two dollars 

 and forty cents ; it can uoav be bought for from two dollars to two dollars and 

 fourteen cents, though it is not in a chemically pure state. This great reduc- 

 tion, which enables the manufacturer and artisan to be plentifully supplied with 

 murexid, is owing to the introduction of 



GUANO. 



This substance is imported from Peru into various parts of North America 

 and Europe, at the rate of between one and two hundred thousand tons per 

 annum. Guano is found in vast quantities in Peru and on many of the cliffs 

 and islands in that part of America between the 13th and 21st degrees of south 

 latitude. It is the excrement of sea-birds, and contains as much as four per cent, 

 of uretric acid. In those regions the sandy soil could ba but unprofitably cul- 

 tivated without the aid of guano. It is known that as early as the twelfth 

 century manuring with guano was practiced there. Under the Incas, guano 

 was considered so valuable that killing the young birds on the guano islands 

 was punishable by death. 



Each of those islands had its superintendent, and each island was assigned 

 to a particular province. From 6,000 to 7,000 tons were annually used in Peru 

 alone ; and Avheu Alexander von Humboldt was exploring America, there were 

 as many as fifty small coasting vessels employed exclusively in the transport 

 of guano. Humboldt took some samples to Europe, where they were analyzed by 

 Klaproth, Fourcray, and Vauquelin. The celebrated traveller and writer also 

 published what he had learned as to the importance of guano to agriculture, 

 but for some time his words remained unheeded. In Germany, Liebig's call 

 upon the cultivators of the soil failed to stir them into activity, and it is even 

 now insufficiently used, even by England, v^hose severely worked land more 

 than almost any in Europe requires such a return of the elements of which 

 years of grain-growing have deprived it. •• • 



Liebig and Woehler were the first chemists to experiment on guano. In the 

 course of their inquiries on the subject of uretric acid they had often been em- 

 barrassed by want of material ; they therefore requested William Kind, an 

 apothecary of Bremen, to procure them some, and in due season received a hun- 

 dred pounds weight from Valparaiso. So much have agriculturists been enlight- 

 ened since that time, that, in several European countries, guano is an article of 

 considerable yearly importation, and the raw material of uretric acid is never 

 wanting. And such is the potency of modern chemistry that guano, so highly 

 offensive to the nostrils in its raw state, is made to yield some of the most deli- 

 cate of the perfumes which are used by the fair and the fashionable. A greater 

 contrast than that presented in this case by the raw material and the article it 

 is compelled to yield can scarcely be imagined. 



The first attempts to render the murexid available for dyeuig purposes were 

 made by Sacc, in Alsace, that high school of the art of dyeing ; and he suc- 

 ceeded in giving to wool an amaranth color far more beautiful than that obtained 

 from cochineal." This induced Schunberger to try a new course of experiments, 

 in which, if he did not entirely succeed, he at least ascertained that white tex- 

 tures could be thus dyed both handsomely and durably. Sacc maintained on 

 this occasion that the coloring matter of the cochmcal, the kermes, &c., has 

 some connexion with murexid. He claimed to have discovered that birds, and 



pecially those of Brilliant plumage, the parrots, for instance, while they are 

 ^oultmg, secrete scarcely a distinguishable trace of uretric acid, but secrete a con- 

 siderable quantity as soon as they recover their full plumage. What, then, 

 becomes of the uretric acid when it is no longer excreted ixom the body? 



26 S 



