514 



GRAYER CREBILLON. 



by cautiously approaching, and remaining quietly on 

 tlie margin of such a stream, we may MT the crawfish 

 industriously bringing from the lower part of their 

 caves the dirt accumulated there ; and this enables 

 us to comprehend the manner in which they origin- 

 ally made their retreats. Upon the two great claws, 

 folded towards each other, and thus forming, with the 

 front of the body, a sort of shelf, the dirt is carefully 

 brought to the surface, and thrown down just where 

 the current will sweep it away. As the substances 

 thus l.n>uht up are very light, it requires a very 

 gentle movement of the animal to avoid spilling, or 

 rather washing off his lading ; and he therefore rises 

 in the gentlest and most circumspect manner. We 

 can testify to the patience with which this labour is 

 continued, as, with the view of observing the opera- 

 tion, we have often quietly pushed in the earth from 

 the edge of the water, wliich they as often have 

 toiled on to remove. It is upon these fresh-water 

 species that the observations have been made, rela- 

 tive to the reproduction of limbs or claws violently 

 broken off. But a short time elapses before a growth 

 or vegetation occurs at the stump or broken part, 

 and a new limb, similar to the original, though some- 

 times rather smaller, is soon formed. This facility of 

 reproduction is found to extend throughout the crus- 

 taceous class. Fresh-water crawfish are regarded by 

 many as furnishing a delicate dish for the table, 

 though their small size, and the trouble of collecting 

 a sufficient number of them, are great obstacles to 

 their being extensively employed in this way. They 

 are preyed upon by various animals, especially by 

 certain birds, whose long bills are adapted to picking 

 them out from the bottom of their dens. 



CRAYER, CASPAR, a Dutch painter, born in 1582, 

 at Antwerp, was a pupil of Raphael Coxie, and be- 

 came, by the study of nature, one of the greatest 

 historical and portrait painters. At the Spanish court 

 in Brussels, he painted the portrait of the cardinal 

 Ferdinand, brother of the king, and received a pen- 

 sion. He established himself in Ghent, where he 

 constantly executed works for the court. He la- 

 boured with industry and perseverance till his 86th 

 year. When Rubens saw his finest painting in the 

 refectory of the abbey of Affleghem, he cried out, 

 " Crayer, Crayer, nobody will ever surpass thee!" 

 The city of Ghent alone had twenty-one altar-pieces 

 by him. In Flanders and Brabant are many of his 

 works, and some of his pictures are in the public col- 

 lections at Vienna and Munich. His paintings are 

 praised for fidelity to nature, excellent drawing, and 

 a colouring approaching the manner of Vandyke. 

 The latter was his friend, and took his likeness. 

 Crayer died in 1669. 



CRAYONS ; a general name for all coloured 

 stones, eartlis, or other minerals and substances used 

 in designing or painting in pastel, whether they have 

 lieen beaten, and reduced to a paste, or are used in 

 their primitive consistence, after being sawn or cut 

 into long, narrow slips. Crayon painting is practised 

 by rubbing on dry colours, hi the manner of chalk, 

 on grounds properly prepared. Vellum or paper is 

 to be employed to receive the colours. The vellum 

 or paper is to be pasted upon canvass extended on a 

 proper stretching frame ; a mixture of powdered 

 pumice-stone and whitening, or prepared chalk, with 

 the addition of some thin size or glue, is then to be 

 laid over the surface of the paper or vellum with a 

 common paste brush, and this is to be repeated 

 twice ; when dry, it must be well rubbed with a 

 piece of flat pumice-stone, to render it even and 

 smooth. The colours used in crayons are the same 

 as those employed in oil-painting, with this differ- 

 ence, that.no white lead is admitted unto their com- 

 position, as it alters and turns black on exposure to 



the air. The whites, therefore, are formed from 

 chalk or plaster of Paris, or the best whitening ; with 

 this addition, all the different degrees of tint are pro- 

 duced, with the mixture perhaps of a little white pipe- 

 clay or soap ; but the best crayons are made in Swit- 

 zerland or Paris, and are to be had at all the colour 

 shops, ready and arranged in sets. The design then 

 being sketched in with pipe-clay, or soft willow char- 

 coal, the crayon is to be laid on in a good full body, 

 in the manner of chalk, and then rubbed in and made 

 smooth with the tips of the fingers ; whatever be the 

 fonn or surface to be filled, it is best to begin with 

 the middle tint ; and in painting flesh, the grey tones 

 should precede the warm. As crayons differ much 

 in their degrees of hardness, arising from the nature 

 of the colours composing them, particularly those 

 made from lakes and blues, it may be found neces- 

 sary occasionally to moisten with spirits of wine such 

 as are found to be very hard and unmanageable, 

 and if too soft, they should be broken down and 

 ground up again with the addition of a little skimmed 

 milk. 



The excellence of crayons consists, in general, in 

 their possessing the necessary degree of softness, for 

 as one colour is always laid on over another, the 

 finger is injured by being employed in rubbing in 

 those which are too hard. There is a sort of paper 

 sold in the shops called crayon paper, which is pecu- 

 liarly adapted for this mode of drawing, and made of 

 a variety of tints. Some artists prefer using tlu's 

 sort of ground. 



Crayons are falling daily into disuse ; first, because 

 they are apt to perish and spoil, if not covered with 

 glass, and, secondly, because the shadows are always 

 opake and mealy-looking. Different methods have 

 been proposed for fixing them, by sprinkling the sur- 

 face of the picture, when finished, with a spirituous 

 solution of isinglass. 



CREAM OF TARTAR (potassa supertartras ; 

 cremor tartari). This salt exists in grapes and in 

 tamarinds. The dregs of wine also contain a consi- 

 derable quantity of it. Cream of tartar contains a 

 very considerable proportion of super-tartrate of pot- 

 assa, about seven or eight hundredths of tartrate of 

 lime, and a small quantity of silica, albumen, iron, 

 &c. It is insoluble in alcohol, but may be dissolved 

 in fifteen parts of boiling and sixty of cold water. It 

 may be rendered much more soluble by mixing with, 

 it a certain quantity of boracic acid or borate of soda, 

 which renders the cream of tartar soluble in its own 

 weight of cold water, and in the half only of this 

 menstruum when boiling. This preparation is known 

 by the name of soluble cream of tartar. Its aqueous 

 solution is soon decomposed by the contact of the air. 

 It is obtained by dissolving in boiling water the com- 

 mon tartar a white or reddish crystalline matter, 

 which forms on the internal sides of the vessels in 

 wliich wine has been kept mixing with it some clay, 

 which precipitates the colouring matter, and then 

 permitting the liquor to crystallize. The action of 

 this substance varies according to the dose in which 

 it is administered. In small doses, it is absorbed, 

 and acts as a temperant ; and, in this quality, it is 

 employed hi jaundice, foulness of the stomach and 

 intestines, &c. In larger doses, it principally spends 

 its action on the mucous intestinal membrane, and 

 induces alvine evacuations, especially when given in 

 powder. Its taste being rather less unpleasant than 

 that of some other neutral salts used in medicine, 

 and its operation being of a very gentle nature, it 

 is very frequently administered. In France, the 

 soluble cream of tartar is generally preferred. See 

 Argal. 



CREBILLON, PROSPER JOLYOT DE, the elder, a 

 French writer of tragedy, who is compared by lus 



