P U Y 



216 



P Y R 



Purpuric appears, and drop the alkaline solution by degrees into 



Acid sulphuric acid, which unites with the potash, and 



leaves the purpuric acid in the form of a light yellow, 



!' u - y de or cream-coloured powder. It is insoluble in alcohol 



xj^!"!^ and ether, and very insoluble in water. It has no 



taste nor smell. The specific gravity is greater than 



that of water. It is dissolved by the mineral acids 



when they are concentrated. According to Dr. Prout, 



its composition is as follows : 



Two atoms hydrogen 

 Two atoms carbon 

 Two atoms oxygen 

 One atom azote 



0.250 

 1.500 

 2.000 

 1.T50 



4.54 

 27.27 

 36.36 

 31.81 



99.98 



Purpuric acid may be obtained from lithic acid by 

 chlorine, and with more difficulty from iodine. 



The purpurate of ammonia crystallizes in quadran- 

 gular prisms, of a deep garnet red colour, by transmit- 

 ted light ; but, by reflected light, their two broadest 

 faces appear of a brilliant green, while their other two 

 faces appear of a dull reddish-brown colour. The pur- 

 puric acid forms other neutral salts with potash, lime, 

 magnesia, strontian, alumina, and almost all the me- 

 tals. Dr. Prout considers the salts as anhydrous, 

 and composed of two atoms of acid and one of base. 

 He conceives that the purpuric acid and its compounds 

 may constitute the basis of many animal and vegetable 

 colours. He remarks, that " some of the purpur- 

 ates, as, for example, that of lime, might be proba- 

 bly used as a paint. They might be also used for 

 dyeing, especially wool and other animal productions." 

 See Philosophical Transactions for 1818, p. 420. 



PUTNEY, a village of England, in Surrey, is situa- 

 ted on the south bank of the Thames, about four miles 

 from London. The church is a small edifice, with a 

 stone tower at the west end. There is here an excel- 

 lent wooden bridge over the Thames, erected in 1729, 

 which cost 23,075, and yields a revenue of above 

 3000 per annum. There is on the common an obe- 

 lisk, built in 1786, to commemorate Hartley's inven- 

 tion for securing buildings against fire. The popula- 

 tion of the parish is 492 houses, and 2881 inhabitants. 



PUY, LE, a considerable manufacturing town of 

 France, and the chief place of the department of the 

 Upper Loire. It is situated on the river Borne, on 

 the side of a hill, which is crowned with a large and 

 picturesque conical rock. The town is poor looking 

 and ill built. It has a large cathedral, and a public 

 library and cabinet of natural history on a small scaled 

 The manufactures are, blankets, lace, linen, silk, and 

 stoneware. There is likewise here a foundry for cop- 

 per vessels. Dyeing is also carried on to a great 

 extent. The chesnut trees thrive here wonderfully, 

 and they furnish a great part of the Lyons chesnuts. 

 Population 15,915. 



PUY DE DOME, the name of a department of France, 

 in Lower Auvergne. It is bounded on the north by 

 the department of the Allier, on the west by that of the 

 Creuse and the Correze, on the north by those of Can- 

 tal and the Upper Loire, and on the east by that of the 

 Loire. It contains about 8450 square kilometers, or 

 428 square leagues. The district of Limagne, form- 

 ing the principal part of this department, extends from 

 thirty to thirty-five myriametres along the Allier, and 

 is one of the most fertile districts of France. Paris 

 j.s supplied with oxen from the fine pasturages of the 



arrondissement of Thiers. The arrondissement of Is- 

 soire is celebrated for its cheese, and produces a great 

 deal of nut oil. The department is watered by the 

 Allier, the Dore, the Sioule, the Couze, the Dolore, 

 and the Veyre. The principal productions of the de- 

 partment are corn, wines, fruits, lint, hemp, brandy, 

 nut oil, cheese, and mineral waters, beside lead, iron, 

 marble, and coal. About 300 tons of iron are obtained 

 annually, and 12,000 tons of coal. The following are 

 the principal towns: 



Pyramids 



Clermont, 



Riom, 



Thiers, 



Ambert, 



Issoire, 



Population. 



24,478 



13,328 



10,605 



0,926 



5,095 



Clermont is the capital of the department. The 

 forests occupy about 96,100 acres, of which two-thirds 

 belong to individuals. The contributions in the jear 

 1803 were 3,656,547 francs. Population 509,444. 'See 

 CLERMONT, Vol. VI. p. 680. 



PUZZUOLI. See POZZUOLI in this volume. 



PYCNITE. See MINERALOGY Index. 



PYRAMIDS, the name given to a series of lofty and 

 stupendous buildings in Egypt, which extend from 

 Cairo to the north, upon a plain about fifty miles long, 

 stretching parallel to the Nile. This plain, which is 

 composed of hard calcareous rock beneath, is about 

 eighty feet above the level of the river. 



The three largest pyramids are in the neighbour- Great py- 

 hood of Ghize or Djiza, viz. those of Cheops, Cephre- ramid O f 

 nes, and Mycerinus, which are surrounded with many Cne P s - 

 others of a smaller size. 



The great pyramid of Cheops has the following di- 

 mensions, according to different authors. 



Number 



Height. 



800 French feet. 

 625 

 600 



499 Eng. feet. 



616 Fr. feet. 



625 do. 



520 



440 



498 ng. feet, 



448 Fr. feet. 



This pyramid is ascended by an uninterrupted series 

 of steps, diminishing from four, to two and half feet 

 high in approaching the top. The breadth of each 

 step is equal to its height. Upon the top there is a 

 platform thirty-two feet square, consisting of nine large 

 stones, about a ton each, though inferior to some of the 

 other stones, which vary from five to thirty feet long, 

 and from three to four feet high. Here the travellers 

 of all ages and nations have inscribed their names in 

 their respective languages. From this platform Dr. 

 Clarke saw to the south the pyramids of Saccara, and 

 on the east of these, smaller monuments of the same 

 kind nearer to the Nile. He remarked also an appear- 

 ance of ruins which might be traced the whole way 

 from the pyramids of Djiza to those of Saccara, as 'if 

 the whole had once constituted one great cemetery. 

 The stones upon this platform, as well as most of the 

 5 



