NOVBMBER, 1901.] 



KNOWLEDGE. 



253 



Umi feet loug and two inches in diameter. These bags 

 when tilled have somewhat tlie appeai'ance of aii 

 enormous Bologna sausage. They arc taken to an apart^ 

 ment where there ai'o a number of open charcoal fur- 

 naces, before each of which there is one principal 

 operator with two assistants. The former grasps one end 

 of the long sausage in his left hand, and slowly revolves 

 it iu front of the fii-e ; at the same time one of the 

 assistants, seated as fai- off as the sausage is long, twists 

 it. in the opposite direction. The roasting before the 

 glowing charcoal soon melts the lao in the portion 

 neirest the operator's hand, and the twisting of the 

 cloth causes it to exude and drop into a trough placed 

 below. The troughs which I saw in use were simply 

 leaves of the American aloe. When a sufRcient quantity 

 in a molten condition is ready in the trough, the 

 operator takes it np in a wooden spoon and places it 

 on a wooden cylinder some eight or ten inches in 

 diameter, the upper half of which is covered with sheet 

 brass. The stand which supports this cylinder gives 

 it a sloping direction away from the operator. The 

 other assistant now stejjs forward holding a strip of 

 the aloe between his hands, and with a r<^pid and 

 dexterous draw of this, the lac is at once spread into 

 a sheet of uniform thickness which covers the upper 

 portion of the cj-linder. The operator now cuts off 

 the upper edge with a pair of scissors, and the sheet 

 is then lifted up by the assistant, who waves it about 

 a moment or two in the air, until it becomes quite 

 crisp. It is then held up to the light, and any im- 

 purities, technically ' grit,' are punched out of the 

 brittle sheet bj' the finger. . . . The sheets arc placed 

 in packing-cases, and when subjected to pressure break 

 into numbers of fragments." 



Previous to the discovery and extensive employment 

 of aniline colours the substance known as lac-dye formed 

 an important and valuable item among oriental animal 

 products. As already mentioned, it is obtained by 

 washing stick-lac in the course of its conversion into 

 shell-lac. Unlike the latter substance it appears, how- 

 ever, to be of exclusively animal origin, being in fact the 

 actual body of the lac-insect, and not a separate secretion. 



In the manufacture of lac-dye in India the red liquor 

 obtained from washing stick-lac is first of all strained 

 through some textile fabric, in order to remove all por- 

 tions of woody matter and other foreign substances. 

 " It is then," to quote once more from Prof. Ball, 

 '■ poured into large vats, where it is allowed to settle ; 

 the sediment is subjected to various washings, and at 

 last allowed to settle finally, the supernatant liquor 

 being drawn off. The sediment, when it is of the 

 proper consistency, is placed in presses, from which it 

 is taken out in the form of hard, dark, pui-ple cakes, 

 with the manufacturer's trade-mark impressed upon 

 them. By the addition of mordants, this dark purple 

 substance yields the most brilliant scarlet dyes, which 

 are not inferior, I believe, to those produced by 

 cochineal itself." 



Of greater repute and of more importance 

 than lac-dye is cochineal, which is the source 

 of artists' carmine and carmine-lake, while when prc- 

 cipita.ttd with a salt of tin, it also yields a splendid 

 scarlet. The cochineal insect, of which the female, like 

 that of the nearly allied lac-insect, alone yields the 

 dye, is originally a native of Mexico, where it is parasitic 

 on the leaves of the prickly-pear. The males of the 

 CoccuB cacti, as the species is called, are minute insects 

 furnished with well-developed wings, feathered antennae, 

 and a long pair of hair-like processes at the hinder 



exti-eniity of the body. On the other hand, the female 

 is a repulsive-looking, wingless creature, with very short 

 posterior hairs, and nearly double the size of her partner. 

 These insects adhere tightly to the smooth surface of 

 tho fleshy leaves of the prickly-pear ; and are not unlike 

 small purple wood-lice in general appearance. 



The following account of the cochineal-hai'vest is 

 extracted from the English edition of Figuicr's " Insect 

 World." " These insects aie collected when the females 

 arc about to lay, that is, when a few young are halxHied. 

 It is when the females are pregnant that they contain 

 the greatest amount of colouring matter. When tho 

 harvest-time has arrived, the cultivators stretch out on 

 the ground pieces of linen at the foot of tho plants, 

 and detach the cochineals from them, brushing tho 

 plants with a rather hard biiish, or scraping them off 

 with a blunt knife. If the season be favourable, 

 the operation may be repeated three times in the course 

 of the year in the same plantation. The insects thus 

 collected arc killed by dipping into boiling water, by 

 being put into an oven, or by being placed on a plate 

 of hot iron. When withdrawn from the boiling water 

 they aJ"e placed on strainers in an aii-y position, first 

 in the sun, and aft,erwards in the shade. During their 

 immersion they lose the white powder with which they 

 are covered in life. In this state they ai-e called 

 ronagridas by the Mexicans. Those that have passed 

 through the oven they tcnn jasiJC-adas ; these are ashy 

 gi'ey-in colour, but those which have been placed on 

 tho hot plate become blackened, and are hence called 

 negras. In commerce three sets of cochineal are recog- 

 nised; first, the maxtique, of a reddish colour, with a 

 moro or less abundant glaucous powder ; secondly, the 

 noir, which is lai^ge, and blackish brown in colour ; and, 

 thirdly, the xi/lvestre, which is smaller and of a reddish 

 colour. This last description, which is gathered fiom 

 wild cacti, is the most highly esteemed of all. Each 

 year there are imported into France 200,000 kilo- 

 grammes of cochineal insects, which represent a value 

 of about three million francs." 



The cochineal trade is chiefly in the hands of the 

 Spanish and the French. By the latter government 

 these insects have been successfully introduced into 

 Algeria, where they yield a large revenue. About the 

 middle of the last ccntui-y the government were accus- 

 tomed to purchase the entire harvest, at the rate of 

 fifteen francs the kilogramme. At a still earlier date 

 they were introduced into the Canaries, where they 

 have also become well established ; but the attempts 

 to acclimatize them in Corsica and the south of France 

 resulted in failure. 



In the early days of civilization, long before America 

 was dreamt of, carmine was fm-nished by two European 

 insects belonging to the family Goccidcc. The first of 

 these is Cermes vermiliu, the kokkos of the ancient 

 Greeks, and the kernies or alkcrmcs of the Arabs and 

 Persians. The females of this species are found adher- 

 ing to the twigs of the kermes oak {Qiiercus corcifern), 

 which grows in dry districts throughout most of the 

 Mc-ditei-ranean countries of Europe. On their native 

 oaks the insects form dry brittle masses, which were 

 (and perhaps still are) collected by the peasants in the 

 south of France. When separated and completely dried, 

 thsy are known as graines de kermes. In appearance 

 they may bo likened to purple cun-ants ; and when 

 subjected to suitable treatment they yield a splendid 

 red dye. 



The second species is the Polish kermes {Porphyro- 

 phyrn pijlonica), which once attained great celebrity 



