"the small guts; and after three hours opening "the dog again, I faw many of the lacteals of a "deep blue colour, several of them were cut, " and afforded a blue liquor, fome of the decoc"tion, running forth on the mefentery. After "this I examined the ductus thoracicus, (on which, "together with other veffels near it, I had on

my return made a ligature) and faw the recep"taculum chyli, and that ductus of a bluish colour; "not fo blue indeed as the lacteals, from the fo"lution mixing, in or near the receptaculum, with

lympha; but much bluer than the ductus used "to be, or than the lymphatics under the liver, "with which I compared it, were*."

Stone blue is a preparation of cobalt, pot-ash, and white lead; which, being converted into glass, is ground into a fine powder. And if such a substance can pervade the lacteals, we may conclude that they are permeable to other bodies, befides thofe defigned for nutrition, and capable of affimilation with the blood. This argument, from analogy, receives great additional force from the known fact that mercury, and various other active remedies, may be conveyed into the body through the abforbents of the fkin, a system of veffels, fimilar to thofe above-mentioned, in their structure, ufes, and termination. In a cafe of hydrocephalus internus, on which I

See Philofoph. Tranf. abridged by Motte, chap. IV. part II. p. 76.

have lately been confulted, a child under one year of age received, by fucceffive frictions, four ounces, fix drachms, and two fcruples of the unguentum cæruleum fortius, between the eighth of February and the feventh of April 1786. One fcruple was administered each time; the operation took up more than half an hour; and the part, to which the ointment was applied, was always previously bathed with warm water; precautions which feemed to fecure the full abforption of the mercury*. I fhould not omit to mention that the child recovered without any symptoms of falivation, and continues perfectly well. Indeed I have repeatedly obferved, that very large quantities of the unguentum cæruleum may be used in infancy and childhood, without affecting the gums, notwithstanding the predifpofition to a flux of faliva, at a period of life incident to dentition. The practicability of curing the bydrocephalus internus is a late and happy difcovery; and perhaps the peculiar efficacy of quickfilver, in this alarming dif

Thirty-feven grains of calomel were given internally, during this space of time, at proper intervals, and in fixteen dofes. The cafe referred to occurred in London, and was under the immediate direction of feveral phyficians of eminence. The ufe of mercury was adopted by my advice; and the estimate of the quantity confumed, as made by the apothecary, has been tranfmitted to me by G. H. Esq. the father of the child.

ease, may reflect fome light on the general rationale of its action. The ftructure of the brain is yet very imperfectly known; but anatomists have fufficiently afcertained, that it is moft copiously supplied with veffels of every order, fo that about one tenth of the whole mafs of blood circulates within it, although the weight of the encephalon does not exceed one fortieth part of the whole body. On this large system of veffels, mercury may be prefumed to act with a force proportionate to its magnitude and extent. And, in the instances when no falivation takes place, it is not unusual for profufe fweatings to occur about the head. An acceleration of growth, also, to an extraordinary degree, is frequently obferved, after the disease has been thus fubdued. In one cafe, which fell under my direction in 1784, a young lady, nine or ten years of age, of a noble family in this county, increased in ftature, two inches, within the space of four months, fucceeding her re

covery.

Whence is it that a medicine, fo irritating as mercury, can be conveyed into the courfe of circulation, when even milk, or the mildest liquors, if transfufed into the blood veffels, have been found to produce convulfions and death? Is it that what paffes by the lymphatics or lacteals

• See Monro on the ftructure of the nervous fyftem, P. 3, folio.

is carried into the thoracic duct, and there mixed with a large portion of the chyle and lymph, by which its acrimony is fheathed and diluted, or its chemical properties changed, before it enters the mafs of blood? For the abforbents of the fkin, and of the intestines, fhould feem to require a capacity to bear the ftimulus of those extraneous bodies to which, in both fituations, they are expofed.

III. Medicines introduced into the course of circulation may affect the general conftitution of the fluids; produce changes in their particular qualities; fuperadd new ones; or counteract the morbific matter, with which they may be occafionally charged. By obfervations on the hæmorrhages, which have been fuftained without deftruction to life; from experiments made on animals, by drawing forth all their blood; and by a compution of the bulk of the arteries and veins; the mafs of circulating fluids has been estimated at fifty pounds, in a middle-fized man; of which twenty-eight pounds are supposed to be red blood. Fluids, bearing fo large a properties to the weight of the whole body, have affuredly very important offices in the animal economy. Endued with the common properties of other fluids, they are fubject to mechanical laws; being variously compounded,

• Vid. Halleri Prim. Lin. fe&t, CXLIX.

they are incident to chemical changes; and, as they are contained in a living vafcular fyftem, their motions become fubject to the influence of nervous energy.

But the prosecution of this fubject will exceed the bounds of the prefent evening's difcuffion: And I fhall referve what I have further to advance upon it to fome future meeting of the Society.

OBSERVATIONS concerning the VITAL PRINCIPLE; by JOHN FERRIAR, M. D.

READ FEBRUARY 7, 1787.

Quibus ipfis noftrum (fc. humanum) ingenium optimè poteft cognofci, quod vilia, fenfibus obvia et facilia, ac fimpliciffima despicit; ad ignota vero, obfcura et magnifica magno impetu fertur. HOFFMAN.

PH

HILOSOPHERS have generally supposed the human body to poffefs a living power, independent of the mind. This opinion arofe at a very early period, and prevailed, with little interruption, till the origin of the eclectic philofophy; the revival and confirmation of the doctrine have been attempted, by some eminent phyfiologifts of our own times. The doctrines of pneumatology have, indeed, little influence

on