1'OR 



POR 



have been very accurately taken. Tlie to- 

 tal population of the 102 departments, into 

 which France was then divided, was stat- 

 ed at 33,104,343 persons, over an extent 

 of about 185,600 square milts. This ac- 

 count included thirteen departments in- 

 corporated with the north of France, 

 four departments in the south, and some 

 smaller acquisitions, comprehending, in 

 the whole 23,790 square miles, contain- 

 ing 5,114,419 inhabitants. 



POPULUS, in botany, poplar, a genus 

 of the Dioecia Octandria class and order. 

 Natural order of Amentaceae. Essential 

 character : calyx of the ament a flat scale, 

 torn at the edge ; corolla turbinate, 

 oblique, entire : female, stigma four-cleft; 

 capsule two celled ; seeds many, pappose. 

 There are eleven species ; among which 

 we shall notice the P. tremula, trembling 

 poplar-tree, or asp, as it is called from 

 the German espe, which is the general 

 name for all poplars ; it lias a green 

 smooth bark ; the leaves at first breaking 

 out are hairy above, and cottony under- 

 neath, but when full grown are smooth. 

 Linnaeus observes that they are rolled in- 

 wards at the edge, having two glands, 

 running one into the other, on the inner 

 side above the base ; he also observes 

 that the leaf-stalks are flatted towards 

 the end, which occasions the perpetual 

 trembling of the leaves with every breath 

 of wind ; the petioles being fiat in the 

 white and black poplars, as well as in this. 

 Dr. Slokes accounts better for the pheno- 

 menon, from the plane of the long leaf- 

 stalks being at right angles to that of 

 the leaves, allowing them a much freer 

 motion than could have taken place had 

 their planes been parallel. The High- 

 landers of Scotland account for it from a 

 superstitious notion that our Saviour's 

 cross was made of this tree, and that 

 therefore the leaves can never rest. 



PORANA, in botany, a genus of the 

 Pentandria Monogynia class and order. 

 Essential character: calyx five-cleft, in 

 the fruit larger ; corolla bell-shaped ; 

 style semibifid, longer, permanent ; stig- 

 mas globular ; pericarp two valved. 

 There is only one species, viz. P. volubi- 

 lis, a native of the East Indies. 



PORCELAIN, a fine sort of eartheif- 

 ware, chiefly manufactured in China, and 

 thence called china-ware. 



The combination of silex and argil is 

 the basis of porcelain : and, with the ad- 

 dition of various proportions of other 

 earths, and even of some metallic oxides, 

 forms the different varieties of pottery, 

 from the finest porcelain to the coarsest 



earthenware. Though siliceous earth is 

 the ingredient which is present in largest 

 proportion in these compounds, yet it is 

 the argillaceous which more particularly 

 gives them their character, as it commu- 

 nicates ductility to the mixture when soft, 

 and renders it capable of being turned in- 

 to any shape on the kuhc, and of being 

 buked. 



The clays are native mixtures of these 

 earths ; but they are often rendered unfit 

 for the manufacture of at least the finer 

 kinds of porcelain, from other ingredi- 

 ents which they also contain. 



The perfection of porcelain will depend 

 greatly on the purity of the earths of 

 which it is composed ; and hence the 

 purest natural clays, or those consisting 1 

 of silex and argil alone, are selected. 

 Two substances have been transmit- 

 ted to Europe, as the materials from 

 which the Chinese porcelain is form- 

 ed, which have been named KAO- 

 LIN and PETUNSE, which see; it was 

 found difficult to procure, in Europe, 

 natural clays equally pure, and hence, in 



Cart, the difficulty of imitating the porce- 

 lin of the east. Such clays, however, 

 have now been discovered in different 

 countries ; and hence the superiority to 

 which the European porcelain has attain- 

 ed. The fine Dresden porcelain, that of 

 Berlin, the French porcelain, and the 

 finer kinds which are formed in this coun- 

 try, are manufactured of such clay, which, 

 from the use to which it is applied, has 

 received the name of porcelain earth, and 

 which appears, in general, to be derived 

 from the decomposition of the felspar of 

 granite. It appears, also, that natural 

 earths, containing magnesia, are used 

 with advantage in the manufacture. The 

 proportion of the earths to each other 

 must likewise be of importance ; and 

 from differences in this respect arise, in 

 part, the differences in the porcelain of 

 different countries, as well as the necessi- 

 ty frequently of employing mixtures of na- 

 tural clays. The argil communicates te- 

 nacity and ductility to the paste, so that 

 it may be easily wrought : the silex gives 

 hardness and infusibility ; and on the pro- 

 per proportion of these depends, in a 

 great measure, the perfection of the com- 

 pound. The proportion of silex in porce- 

 lain of a good quality is, at least, two- 

 thirds of the composition ; and of argil, 

 from a fifth to a third. Magnesia is of 

 utility, by lessening the tendency which 

 the composition of silex and argil alone 

 has to contract in baking, and which is 

 convenient in the manufacture. In the 



