PEREIRIN. 



PERIMETER. 



394 



by M. Piorry and others : they are composed of small plates of cork, 

 india-rubber, light wood, or ivory, which being held by their edges or 

 by a handle, are placed on the part to be examined, and struck with 

 the fingers, or with a small hammer. Whether the hammer and plexi- 

 meter or the fingers are used, care should be taken that the blows are 

 always given with the same or an exactly estimated degree of force, and 

 that they should fall perpendicularly to the surface of the organ to be 

 examined. 



Percussion is chiefly employed in the diagnosis of diseases of the 

 lungs, heart, and abdominal organs. [PHTHISIS; HEART, DISEASES 

 OF, &e.] 



The lungs being chiefly composed of tubes and cells filled with air, 

 there is a certain degree of resonance when the chest over any part of 

 them is struck ; but the character of the sound varies somewhat both 

 in intensity and in tone, according to the part of the chest examined, 

 and the thickness and softness or hardness of its walls : in all parts 

 however, when the lungs are healthy, there is resonance. When 

 however the lung is covered by fluid, or has the quantity of air in it 

 lessened by obstruction of the air-tubes, or by deposits of fluid or solid 

 substances in or around the cells, the resonance of the chest directly 

 over the part affected is diminished or entirely lost, and in extreme 

 cases the only sound obtained by percussion is the dull sound of the 

 contact of the fingers with the wall of the chest. When, on the other 

 hand, the air-cells are dilated, and the lungs contain a greater pro- 

 portion of air than i natural to them, as in emphysema of the lungs, 

 the resonance of the chest is in a corresponding degree increased. The 

 various degrees between perfect dullness, such as occurs when the lung 

 is covered by fluid [HYDROTHORAX], or rendered solid by inflammation 

 [Lrscs, DISEASES OF], or by tubercular deposition [PHTHISIS], and the 

 highest degree of resonance in emphysema are numerous, but are of 

 course appreciable only by a very practised ear and hand. To them 

 the evidence they afford is scarcely less valuable than that obtained 

 from the use of the stethoscope, with which the practice of percussion 

 should, in all diseases of the chest, go hand in hand. 



In the healthy state, the chest, when struck over the region of the 

 heart, emits a duller sound than that which proceeds from the rest of 

 its walls. In the natural size of the heart this region occupies a space 

 of an inch and a half or two inches square, situated just to the left of 

 the sternum, at the level of the fourth and sixth ribs. When either 

 the heart itself is enlarged, or a quantity of fluid is accumulated in the 

 pericardium, the extent of this less resonant region is increased in a 

 corresponding degree ; but the changes of sound which it emits depend 

 greatly on the coincident condition of the lungs, and the extent to 

 which their anterior margins overlap the front of the heart. 



By percussion on the abdomen one may obtain information, approxi- 

 mating to truth, of the size of all the solid organs, by the extent of 

 the dullness of sound in their respective regions ; and of the degrees of 

 inflation, and even of the nature of the contents of the digestive canal 

 and the peritoneal cavity, whether solid, liquid, or aeriform; but the 

 evidence thus obtained is on the whole less definite in the diseases of 

 the abdominal organs than in those of the heart and lungs. 



(M. Piorry, De la Percuaion mediate, Paris, 1828 ; Bennett, Intro- 

 duction to the Study of Clinical Medicine, 1860 ; Weber, On Autcuilation 

 and Pomatum, translated by Cockle, 1854.) 



PEREIRIN. An alkaloid of febrifuge qualities, but of uncertain 

 composition, found in the bark of the t'allaia inedita. 



PERFUMERY, considered as a branch of manufacture, is chiefly 

 chemical in its nature ; but its chemistry is of that peculiar kind 

 which relates almost wholly to the odour of substances, whether 

 animal, vegetable, or mineral, whether natural or artificial. The 

 relations of the substances to light and colour, or to solidity and 

 liquidity, are of quite secondary importance ; so long as the invisible 

 odour-bearing particles are given off', and conveyed by the air to the 

 organ of smell, all substances may take rank among perfumes except, 

 of course, such as yield an unpleasant odour. It is generally admitted 

 that perfumes, if pleasant, exercise a cheering and exhilarating 

 influence on the human system, and revive the spirits when fatigued 

 or depressed. The connection between the brain and the organ of 

 smell is too close to allow the former to be quite uninfluenced by 

 anything which affects the latter. 



Without touching here upon the physiological or medical relations 

 of perfumes, we shall say a few words concerning their production as 

 a branch of trade. Linnoeiis divided scents into seven kinds, Touray 

 into five, and De Haller into three. Mr. Rimmel, himself a perfumer, 

 who read a. paper on this subject before the Society of Arts in 1860, 

 groups the scents mostly used in perfumery under eighteen kinds, 

 represented by the following types: rose, jasmine, orange-flower, 

 tuberose, violet, balsam, spice, clove, camphor, sandal, citrine, lavender, 

 mint, aniseed, almond, musk, amber, and fruit flavour. The principal 

 branches of the perfumery trade, connected with these eighteen kinds 

 of scents, are the making of scented soaps, the compounding of 

 perfumes, and the production of numerous minor articles for the 

 toilet. Perfumed soaps are made on the same general principle as 

 common soap, but in smaller quantity, with greater care, and with 

 the addition of certain odoriferous substances. The removal of the 

 excise restrictions has been the cause of much improvement in this 

 art, the perfumer being at liberty to make more varied experiments 

 than were before permitted. The perfumed liquids and pastes are 



very numerous. The basis of most of them is obtained by treating 

 with alcohol the pomade or oil extracted from flowers. There are 

 also many toilet-waters, such as eau-de-cologne, and the once-famous 

 Hungary water, manufactured chiefly with an alcoholic basis. Lavender- 

 water was formerly distilled with alcohol from fresh flowers; but 

 it is now made more economically by digesting the essential oil in 

 alcohol. 



The substauces mostly used in the manufacture of perfumery are 

 of animal origin, such as musk, civet, and ambergris ; floivers, such as 

 jasmine, rose, orange-flower, violet, jonquil, narcissus, &c. ; herbs, such 

 as the leaves and stalks of peppermint, fennel, thyme, marjoram, spike, 

 rosemary, verbena, &c. ; fruits of the citrine kind, such as orange! 

 lemon, and cedrat ; apices, such as cassia, cinnamon, cloves, mace, and 

 nutmeg; -.foods, such as sandal- wood, rosewood, cedar-wood, and 

 sassafras ; roots, such as orris-root and the Indian kus-kus ; seeds, such 

 as aniseed, dill, and carraway ; and gums, such as benzoin, styrax, 

 myrrh, camphor, and several balms or balsams. Most of the odoriferous 

 principles are extracted by distillation ; but the aroma of flowers is 

 now very often obtained by the agency of fatty bodies. Scented 

 pomades and oils are produced either by maceration or by absorption ; 

 the former for the less delicate flowers, and the latter for such as 

 the jasmine and tuberose, which cannot bear a high degree of heat 

 without losing their scent. Mr. Rimmel states that at three towns 

 in the South of France there are no less than 100 firms engaged in 

 obtaining pomades and essential oils from flowers, consuming annually 

 the following quantities and value of flowers : 



1,760,000 Ibs. Orange flowers .... 38,000 



590,000 , Rose flowers . . . . . 10,000 



110,000 , Jasmin flowers .... 6,000 



66,000 , Violets 7,000 



66,000 , Cassia 10,000 



33,000 , Tuberose 3,000 



The rose-water, orange-flower-water, scented pomades, and essential 

 oils, obtained from these materials have a value of nearly 300.000/. 

 M. Piver, of Paris, adopts a peculiar mode of obtaining the perfumes 

 of plants by bringing a condensed current of air to bear upon the 

 scented particles, and forcing them to combine with a kind of ointment. 

 M. Millon, another French perfumer, extracts the aroma of flowers 

 by means either of ether or sulphuret of carbon, both of which are 

 powerful solvents. 



The extent of this manufacture is much larger than is generally 

 supposed. Mr. Rimmel states, from data which he has been able to 

 obtain, that there are 40 manufacturing perfumers in London alone, 

 employing from 20 to 100 hands each; that our imports of essential 

 oils and perfumery materials reaches 200.000J. annually; that the 

 retail value of all the perfumery made in the United Kingdom cannot 

 fall far short of 1,000,000/. a year ; and that there are 80 manufacturing 

 perfumers in Paris, employing 2000 to 3000 hands. Mr. Rimmel 

 gives the names, place of production, and form or condition, of about 

 seventy substances employed by the manufacturing perfumer. The 

 prices affixed to some of these are extraordinary civet, II. per oz. ; 

 musk, 11. 10. per oz. ; ambergris, 21. per oz. ; essential oil of Acacia 

 farnetiana, 41. per oz. ; essential oil of jasmine, 6/. per oz. ; while attar 

 of roses, in its choicest and most concentrated form, runs up to 12/. 

 per oz., or threefold the value of pure gold, weight for weight. 



It is worthy of mention, that, although manufacturing perfumers, 

 such as Mr. Rimmel in the paper above adverted to, and Mr. Septimus 

 Piesse, in a recent volume relating to the subject, dwell chiefly on the 

 obtaining of perfumes from flowers, fruits, and other pleasant sub- 

 stances; chemists are well aware of methods by which perfumes can be 

 obtained in a very different way, and from substances which do not at 

 all accord with the names given to the perfumes. Dr. Lyon Playfair, 

 in his lecture on the Results of the Great Exhibition of 1851, said : " A 

 peculiarly foetid oil, termed fusel oil, is formed in making brandy and 

 whiskey ; this fusel oil, distilled with sulphuric acid and acetate of 

 potash, gives the oil of peart. The oil of apples is made from the same 

 fusel oil, by distillation from sulphuric acid and bichromate of potash. 

 The oil of pine-apples is obtained from a product of the action of 

 putrid cheese on sugar ; or by making a soap with butter, and distilling 

 it with alcohol and sulphuric acid ; and is now largely employed in 

 England in making pine-apple ale. OU of grapes and oil of cognac, used 

 to impart the flavour of French cognac to British brandy, are little else 

 than fusel oil. The artificial oil of bitter almonds, now so largely 

 employed in perfuming soap, and for flavouring confectionary, is pre- 

 pared by the action of nitric acid. Many a fair forehead is damped 

 with eau de millejleurs, without knowing that its essential ingredient is 

 derived from the drainage of cowhouses." This lecture elicited some 

 objections, on the ground that, although agreeable scents may be 

 obtained from offensive substances, it does not follow that they are so 

 in practice ; but probably the manufacturer who went to such sources 

 would not be likely to own it publicly. 



PERIBOLUS. [TEMPLE.] 



PERICARDITIS. [HEAKT, DISEASES OF Tin:.] 



PERIGEE, the point of the moon's orbit in which she is nearest to 

 the earth. 



PERIHE'LION, the point of the earth's orbit in which it is nearest 

 to the sun. [APHELION.] 



PERI'METER, the circuit, or bounding line, of ft plane figure ; a 



