CAN 



CAO 



by attracting the electric fire from the 

 clouds during a thunder-storm, verified 

 Dr. Franklin's hypothesis of the similari- 

 ty o lightning and electricity. Next year 

 his paper, entitled ' Electrical Experi- 

 ments, with an Attempt to account for 

 their several Phenomena," was read at 

 the Royal Society. In the same paper 

 Mr. Canton mentioned his having disco- 

 vered, by many experiments, that some 

 clouds were in a positive, and some in a 

 negative state of electricity : a discovery 

 which was also made by Dr. Franklin in 

 America much about the same time. 

 This circumstance, together with our 

 author's cdnstant defence of the doctor's 

 hypothesis, induced that excellent philo- 

 sopher, on his arrival in England, to pay 

 Mr. Canton a visit, and gave rise to a 

 friendship which ever after continued 

 between them. Mr. Canton was a con- 

 tributor to the Philosophical Transac- 

 tions, and, among many other papers, he 

 sent, in 1765, an account of the transit of 

 Venus of the 6th of June that year, ob- 

 served in Spital Square. On the loth of 

 December, the same year, another curi- 

 ous addition was made by him to philo- 

 sophical knowledge, in a paper, entitled 

 "Experiments to prove that Water is 

 not incompressible." And on Nov. 8, the 

 year following, were read before the So- 

 ciety, his farther "Experiments and Ob- 

 servations on the Compressibility of Wa- 

 ter, and some other fluids." These expe- 

 riments are a complete refutation of the 

 famous Florentine experiment, which so 

 many philosophers have mentioned as a 

 proof of the incompressibility of water. 

 For this communication he had a second 

 time the Society's prize gold medal. Mr. 

 Canton was a contributor to many other 

 publications, particularly to the Gentle- 

 man's Magazine. In every period of his 

 life he was an ardent promoter of useful 

 science ; and while philosophy lives, the 

 name of Canton will not be forgotten. 

 He died of the dropsy, in his 54th year, 

 on the 22d of March, 1/72. 



CANTONING, in the military art, is 

 the allotting distinct and separate quar- 

 ters to each regiment of an army ; the 

 town where they are quartered being di- 

 vided into so many cantons, or divisions, 

 as there are regiments. 



CANTUA, in botany, a genus of the 

 Pentandria Monogynia class and order. 

 Calyx three to five-cleft ; corolla funnel- 

 form ; stigma three-cleft ; capsule three- 

 celled, three-valved many seeded ; seeds 

 winged. There are four species, natives 

 f America. 



CANVASS, in commerce, a very clear 

 unbleached cloth of hemp, or flax, wove 

 very regularly in little squares. It is 

 used for working tapestry with the 

 needle, by passing the threads of gold, 

 silver, silk, or wool, through the inter- 

 vals or squares. This also is the name 

 of a coarse cloth of hemp, unbleached, 

 somewhat clear, which serves to cover 

 women's stays, also to stiffen men's 

 clothes, and to make some other of their 

 wearing apparel, &c. It is likewise the 

 name of a very coarse cloth made of 

 hemp, unbleached, serving to make 

 towels, and answering other domestic 

 purposes. It is also used to make sails 

 for shipping, 8cc. 



CAOUTCHOUC, or, as it is usually, 

 though improperly named, elastic gum, 

 is a vegetable matter, which, in several 

 of its physical qualities, as well as in its 

 chemical relations, has some similarity to 

 vegetable gluten, and which so far agrees 

 both with it and albumen, as to approach 

 in the nature of its composition to animal 

 matter. 



The substance to which the name of 

 caoutchouc, or elastic gum, has been 

 more particularly given, was brought 

 from Spanish America, in the form of 

 hollow spheres or bottles, in which state 

 it is still imported into Europe ; it was 

 evident, therefore, that it had undergone 

 some artificial preparation. Condamine 

 gave the information, that it is the inspis- 

 sated juice of a tree belonging to the 

 family of the Euphorbia, which has since 

 received the botanical name of Havea 

 guianensis, or Havea caoutchouc. Inci- 

 sions are made in the bark of this tree: 

 a milky juice exudes, which is collected. 

 It is applied in successive coatings over 

 a mould of clay ; is dried up by exposure 

 to the sun, and afterwards by being placed 

 in the smoke from burning fuel ; when 

 dry, the clay mould is crushed, and the 

 fragments extracted, and in this manner 

 the spherical bottles are formed. It has 

 since been discovered, that caoutchouc is 

 not exclusively the produce of this vege- 

 table ; but that it is furnished likewise by 

 other plants, either perfectly the same, 

 or with very slight variations of properties. 

 It is obtained in large quantity from the 

 Jatropha elastica, a native likewise of 

 different provinces of South America. 

 Fourcroy procured specimens of the 

 juice of the caoutchouc, in the state in 

 which it exists previous to its inspissa- 

 tion, from the Island of Bourbon, from 

 Cayenne, and the Brazils, and examined 



