PER
The proportion of pcrfpirat'wn to urine is increafed by all thofe exercifes which increaTe the motion of the blood, and warm the (kin. Dr. Bryan RMnfon of the animal (Econo- my, p. 280.
We have an account of a perfon, who by patting many nights in aftronomical {peculations, had his perforation fo obftrucled by the cold and damp of the air in Holland, that a fliirt he had worn for five or fix weeks was as clean as if it had been worn but one day. The confequence of this was, that he gathered fubcutaneous waters, but was cured in time. Phil. Tranf. N° 8. p. r 3 8.
We have feveral obfervations, experiments, and tables, re- lating to the quantity of perfphatim, urine, and {tool, in South Carolina, by Dr. John Lining. See Phil. Tranf. N l> 470 and 475.
FERTICA, a fort of comet, being the fame with Veru. See the article Veru.
Pjjrtica, among the Romans, a long rod. for beating the fruit from trees. It was Kkewife ufed for a long meafure. See Perch, Cycl.
PERVIGILIA, in antiquity, an appellation given to nocturnal feftivals, celebrated in honour of feveral deities, as Ceres, Venus, Fortune, &c. They were fo called becaufe the nights were fpent in waking.
PERVINCA, periwinkle, in botany, the name of a genus of plants, the characters of which are thefe : The flower con- fifts of one leaf, and is of the funnel-fhapcd kind, but fo very wide at the mouth, that it approaches to the faucer- fbaped ones, and is divided into feveral fegments at the rim. The piftil arifes from the cup, and is fixed in the manner of a nail to the hinder part of the flower: this, afterwards, becomes a feed veflel, compofed of two capfules, contain- ing an oblong feed, ufually of a cylindric figure, and ful- cated. See Tab. 1. of Bot. Clafs 2.
The fpecies of peru'tnea, enumerated by Mr. Tourncfort, are thefe : 1. The common, broad-leaved periwinkle, with blue flowers. 2. The common broad-leaved periwinkle, with white flowers. 3. The common narrow-leaved penwinkle^ with blue flowers. 4. The common narrow-leaved peri- winkle, with white flowers. 5. The common narrow-leaved periwinkle, with red flowers. 6. The common narrow- leaved periwinkle, with double blue flowers. 7. The com- mon narrow-leaved periwinkle, with double flowers, of a deep purple. 8. The variegated double flowered periwinkle. 9. The broad-leaved variegated periwinkle- And 10. The narrow-leaved variegated periwinkle. The tree called padrus, approaches very much to this genus. Toarfi. Inft. p. r 19. The peTuincts are eafily known, even when not in flower c feed, by their branches being long and trailing, and the: leaves fmooth and giofty, and approaching to the fhape of bay-leaves. Thefe plants feldom ripen their fruit; and the way to make them do it is, to plant them in a fmall pot, and cut off all the trailing branches; by which means the nouriihment will be carried up to the ripening the fruit, Tourn Inft. p. 120.
PERUVIAN bark (Cycl)— The virtues of this medicine are at this time fufficientiy known; but the largenefs of its dofe in the common forms of powder, or infufion in wine or water, are great difadvantages ; and our common method of giving it in the extract: or refin, as we prepare them, not certain, and have their inconveniency.
Mr. Geoffroy has attempted a method of giving the bark in all its efficacy, without its ill tafte, and in one third of the ufual dofe, by means of his dry extract:; twenty four grains of which, it is very certain, contains the whole efficacy of a dram of the choiceft hark in powder ; and is found by experience to be wholly as efficacious, as certain, and as fpeedy, and really poffefles all that the juices of the ftomach can extract from thrice the quantity of powder, without loading it with fo large a quantity of ufelefs matter. The experiments this gentleman made to be aflured of what was the efficacious, what the ufelefs part of the bark, and what thequantity of each m the whole, were thefe. He put -into a matrafs a dram of choice bark in fine powder, and pouring on it an ounce and a half of rectified fpirit of wine, fet the veffel in a balneum marice till the fpirit was high co- loured, and had extracted all the tincture it could, and fil- tering this tincture, and evaporating it on a China-plate in a balneum marine, he obtained twenty grains of a dry ex- tract; and then putting on two ounces of water on the re- maining powder, he drew what tincture he could by this means, and evaporating that in like manner, he obtained three grains and a half of extract in the like dry form. Thus, by the niceft procefs, twenty-four grains were all that could be feparated of the efficacious matter from a dram of ba'k, and the remaining powder, which was perfectly in- fipid, weighed as much as was required to make up the dram, excepting fix grains, which the author fuppofes to have been the fibrous and infipid powder remaining in the filtre.
Hence it appears very evident, that when we take the bark in fubilancc, it is only about a third part of what we are forced to fwallow that can be of any ufe to us; and that Suppl. Vol. II. 2
PER
the fame portion is all we can expect in the virtues of any decoction or infufion of it.
The refin of the bark is of fuch a nature, that it is capable of being penetrated by, and fufpended in boiling water, pour- ed on the fubftance in fine powder ; and fo long as this wa- ter retains a certain degree of" heat, it remains fufpended and invifible in it, and the- water is of a clear brown ifli co- lour; but when the liquor becomes cooler, the refin can be no longer fufpended, the whole becomes milky, and the re- fin precipitates itfelf.
Wine, which is a liquor partly aqueous, partly faline, and partly fpirituous, is a menftruum much properer to extract: the virtues of the bark than mere water, as it is much more able to difiblve the juices or fap condenfed and infpiffated in the bark of the tree ; and for this rcafon a ftrong infufion of bark in this menftruum remains dear, and keeps the refin fufpended when cold. Thus it is the fire alone which can fufpend the refin in a watry infufion of the bark; and in a vinous one, the fpirituous and inflammable part of the li- quor does the fame thing : and as the refin of the bark, which there is great reafon to believe poflefles all the vir- tues of that medicine, is wholly precipitated fnm watry in- fufions when cold, it is plain that there can be very little dependance placed on the common clear infufions in this menftruum : the remaining tafte in thefe infufions is only a faint bitternefs, which arifes from the gummofe and faline parts of the dried juices of the bark-, the whole concrete which alone poffeffes the virtue of the medicine, be- ing of the nature of thofe bodies properly called gum rejins; which are but very imperfectly foluble in water, and of which wine is the proper difTolvent.
In making the dry extract: by means of water, the fame au- thor put a dram of fine powder of pick'd bark into a large quantity of water, and keeping it in a confiderable heat in a matrafs twenty-four hours, and after that, filtring the li- quor as hot as pofUble, that the refin might not coagulate, he fet it to evaporate on a balneum marise in China-vefTels ; the refin foon began to fcparate itfelf, and a pellicle appeared on the furface of the liquor, of all the changeable colours of the breaft of a pigeon ; and this covering the extract when dry, made it appear as if gilt or browned over. This in- fufion from a pint and half of liquor, yielded twenty grains of extract perfectly dry ; and an ounce and half of fpirit of wine being poured on the remaining powder, when it had extracted all the tincture it could, left only three grains of extract ; fo that the rcfult of this procefs was much the fame with that begun with fpirit of wine ; and from the whole it appears very evident, that by this method of management, the whole virtue of the bark may be given in a third part of the dofe. Memoirs Acad. Science Par. 1738. Peruvian-bark has been found very effectual in preventing colds. The method in which it was ufed, in a cafe men- tioned in the Philofophical Tranfactions, was, . after due preparation, by bleeding or purging, to take two ounces of it every fpring and fall. F,y this method, an habitual taking of cold, and a confequent fore throat was cured. Phil. Tranf. N° 478- P- 3-
We have many accounts of the great effects of the peruvian- bark in the cure of gangrenes and mortifications. See Med. EfT. Edinb. Vol. 3. Art. 5. or its Abridgment, Vol. j. P* *75i feq- We have alfo feveral accounts of the good ef- fects of this medicine in ulcers and the fmall pox. See Med. EfT. Vol. 5. Art. 10. or Abridgment, Vol. 1, p. 187. Many inftances are recorded in medical writers of the jaun- dice, dropfy, afthma, and all the train of nervous diforders, brought on in a fuiprifingly fhort time after an injudicious adminiftration of the bark: among others the curious may confult the Med. Eft*. Edinb. Vol, 4. Art. 24. The perwuian-bark is difcovered to be effectual in the cure of mortifications from an internal caufe. The hiftory of this difcovery is: In 1715, Mr. Rufhworth, furgeon in Northampton, gave it to a patient labouring under a mor- tification ; and having afterwards other proofs of its good effects in this difeafe, communicated his difcovery in 1731. Mr. Amyand foon tried it in fuch cafes, and found it fuc- cefsful in feven. Mr. John Douglas confirmed this by the hiftory of a patient of his, which he publifhed in 1732 ; and Mr. Shipton foon after related his fuccefs by this medicine, to the Royal Society. Mr. Rufhworth and Mr. Amy- and confine its ufe to mortifications, from an internal caufe; the former thinks it is not proper in all cafes of that kind, particularly where there is no intermiffion of the fever. Mr. Douglas feems to think it will fucceed in all mortifica- tions. All thefe three gentlemen gave half a dram for a dofe every fourth hour. Mr. Shipton increafed the dofe to two fcruples, and gave it while the fever continued. He propofed to have it tried in nomas, phagedena;, herpes, or other chironian ulcers. Mr. William Arrot, who lived a confiderable time in Peru, defcribes the tree from which the peruvtan-bark is got.
It grows in the country between two and five degrees fouth
latitude ; it is tall, without branches to near the top, where
it fpreads out into a hemifphere ; its bark is of a dark colour
i Ee on
