516 PATINA 



eation of the agent which produced them. The presence of even traces of free 

 sulphuric acid in the paper would rapidly loosen its texture, the paper would gradu- 

 ally fall to pieces, and one of the most important applications which suggest them- 

 selves, viz. the use of vegetable parchment in the place of animal parchment for legal 

 documents, would thus at once be lost. The paper was found to be entirely free from 

 this acid. 



' The absence of free sulphuric acid in the parchment-paper was, moreover, estab- 

 lished by direct experiment. The most delicate test-papers, left for hours in contact 

 with moistened vegetable parchment, did not exhibit the slightest change of colour.' 



PARIAN. See POTTERY. 



PARIS BLUE. A bright blue obtained by heating aniline with chloride of tin. 

 See ANILINE. 



PARIS RED. A fine iron rouge employed for polishing. 



PARKSINE. A preparation so called from the inventor, Mr. Parks of Bir- 

 mingham, was exhibited at the International Exhibition of 1862. It was made 

 by incorporating castor oil, collodion (gun-cotton dissolved in ether), and wood- 

 spirit. The mixture gradually solidifies, and eventually becomes a hard mass. 

 While in the pasty condition it was moulded into a great variety of forms. It has 

 not, however, taken its place as a manufacture. See OXIDISED OILS. 



PARQUETRY, Parquetage. Inlaid flooring. In most cases thin veneers are cut 

 into geometric forms, and cemented to the planks which are to form the floors. Lately 

 the Messrs. Arrowsmith have introduced their ' solid parquetry,' in which the wood 

 is cut of the required thickness, and ingeniously joined together in geometric patterns. 

 See BUHL ; MAHQUETKY ; REISNEB. 



PARTING. See GOLD and SILVER, REFINING of. 



PARTRIDGE-WOOD. The wood of several trees appears to be imported 

 under this name. It is principally used for walking- canes, and for umbrella- and 

 parasol-sticks. 



PARVOLINE. A volatile nitryle base found in the naphtha from the Dorset 

 Shale. It is isomeric with cumidine. It is the highest known member of the pyridine 

 series. 



PASTEL is the French name of coloured crayons. Also a dye-stuff; allied to 

 INDIGO. 



PASTES, or Factitious Gems. (Pierres precieiises artificielks, FT. ; Glaspasten, 

 Ger.) See GEMS, ARTIFICIAL. 



PASTILLE is the English name of small cones made of gum-benzoin, with 

 powder of cinnamon and other aromatics, which are burned as incense, to diffuse 

 a grateful odour, and conceal unpleasant smells in apartments. Pastille is the French 

 name of certain aromatic sugared confections ; called also tablettes. See PERFUMERY. 



PATCHOULY. Pachupat or Patscha-pat. The herb, Pogostemon Patchouli, 

 which is, on account of its pungent odour, used in perfumery. It is a herb-like 

 plant, growing very much like sage, indigenous to Northern India ; it is also found 

 in China. 



The plant grows readily in the hothouses in England ; specimens are to be found 

 at Kew and other gardens. The leaves have long been in use as a perfume, and pre- 

 ventive of moth. India-shawls used to be packed with patchouly, on account of its 

 being inimical to vermin, and so efficacious in preserving them during a long voyage ; 

 it was thus patchouly was first introduced into Europe. 



When the patchouly-plant is distilled it yields a dense essential oil, to which it 

 owes its odour ; this dissolved in alcohol, in the proportion of 2 ounces to 1 gallon 

 of spirit, forms the ' essence of patchouly ' of the shops. The essential oil of pat- 

 chouly is one of the least, volatile of any known ; hence it is one of the most 

 persistent of perfumes from plants. Under the ordinary conditions, the essential oil 

 of patchouly is a fluid, and will not congeal, except by an excessively low tempera- 

 ture ; but if the plant be distilled after it has been gathered several years, more than 

 half the product will assume a crystalli sable form, far less fragrant than the newer 

 fluid essential oil, and would probably be quite odourless if repeatedly crystallised 

 from alcohol. 



The crystals of patchouly are rhombic-formed, with pyramidal summits ; chemically 

 they resemble camphor in composition. When the fluid essential oil of patchouly is 

 submitted to fractional distillation, there comes at the highest temperature a peculiar 

 blue body, termed by Piesse azvleve, resembling the blue in the essential oil of wild 

 camomile ; it requires, however, further examination. See PERFUMERY. 



PATENT YELLOW. An oxychloride of lead ; called also Turner's Yellow 

 and Montpelier Yellow. See CASSELL YELLOW. 



PATINA. The green coating carbonate of oxide of copper which covers an- 

 cient bronzes and copper medals. True patina is an arvgo, or verdigris, produced by 



