134 PHILOSOPHICAL TRANSACTIONS. [aNNO l666. 



country abounds. And particularly the size and structure of the aqueducts 

 made about Constantinople by Solyman the Magnificent, &c. 



Optic Glasses made of Rock Crystal. By Eustachio Divini. 



iV" 20, p. 362. 



Though it be commonly believed that rock crystal is not fit for optic glasses, 

 because there are many veins in it ; yet Eustachio Divini made one of it, 

 which he says proved an excellent one, though full of veins.* 



4n Account of the Use of the Grain of Kermes for Coloration. By 

 M. Ferny, Apothecary at Montpellier. N"" 20, p. 362. 



The grain of kermes is here described to be an excrescence -f- growing upon 

 the wood, and often upon the leaves of a shrub, J plentiful in Languedoc, and 

 gathered in the end of May and the beginning of June, full of red juice. Two 

 uses are mentioned of this grain, the one for medicine, the other for the dyeing 

 of wool ; of which last alone notice is here taken. 



They take the kermes when ripe and spread it upon linen, turning it at first 

 (whilst it abounds in moisture) twice or thrice a day, to prevent its heating. 

 When there appears red powder among it, they separate it, passing it through 

 a sieve ; and then again spread out the grain upon the linen, until there be 

 perceived the same red powder : and at the end, this red powder appears about 

 and on the surface of the grain, which is still to be passed through a sieve till 

 it render no more. 



In the beginning, when the small red grains are seen to move, as they will 



* It is a question whether those were true veins or only superficial strictures and slight scratches. 



t These grains or excrescences, as they are called, are produced by an insect termed by naturalists 

 coccvs ilicis. The female insect punctures the bark and leaves of the shrub on which it is found ; de- 

 posits its eggs in a sort of nidus thus formed, loses its original shape, and dies. Its reliquiae, with the 

 contained eggs, acquire the appearance of grains or excrescences (analogous to gall-nuts) from which 

 issue, after a certain time (if no measures are taken to destroy them) a number of young insects. 

 The red-powder, mentioned in tlae subsequent part of this paper, consists of larvae destroyed by the 

 process of sprinkling the grains with vinegar and afterwards drying them. 



+ The tree or shrub on which the kermes insect is found is the quercus cocci/era, Linn. In the 

 South of France, and in some of the provinces of Spain, numbers of people, chiefly women, (who 

 for this purpose let their nails grow) are employed in picking these insects from the leaves and 

 branches of this species of oak. They are used for dyeing woollen cloth of a scarlet colour, and 

 constitute an article of commerce of no small consideration to both the above-mentioned countries. 

 The colour they give is more durable than that of cochineal, but not so bright j hence a more fre- 

 quent use of the latter in modem times. 



