Memoirs for the natural history of humane blood, especially the spirit of that liquor by Robert Boyle.

The VI. (Secondary) Title. Of the Consistence and Specifick Gra∣vity of the Spirit of Humane Blood.

TO the Consistence of the Spirit of Humane Blood, taken in the more laxe sense of the word Con∣sistence, one may refer its Specifick Gravity, (as that is usually propor∣tionate to the Density of Bodies,) the greater or lesser degree of Fluidity that belongs to the Liquor as a Mass, and the greater or lesser Subtilty of the Minute Parts whereof it is com∣pos'd,

or wherein it abounds.

And as to the first of the Three At∣tributes, we have noted to be referrable to the Consistence of our Spirit; Gra∣vity is a Quality that is so radicated, if I may so speak, in the nature of Vi∣sible Fluids or Liquors, and does so obstinately accompany them, that I durst not omit to examine the Spe∣cifick Gravity (that is, the Gravity in proportion to the Bulk) of Spirit of Humane Blood; though by reason of the small quantity I had of it, I could not make use of the same In∣struments, that I was wont to em∣ploy in Hydrostatical Tryals, where I was not so stinted in the Liquor to be examined. But however I made a shift to make a Tryal of this kind, by which I found, that a compact body weighing fifty eight Grains in the Air, and in Water six Grains and three fourth parts weighed in Recti∣fied Spirit of Humane Blood, but five Grains and one fourth part. And on this occasion I shall tell you,

what I presume, you did not expect, which is, that notwithstanding the Volatility of our Spirit of Blood, I found that a pretty large piece of Amber being put into it, did not, as most men would confidently expect, fall to the bottom of the Liquor, but kept itself floating at the upper part of it, and if plung'd into it would emerge.

The next Quality we refer'd to the Consistence of our Spirit of Blood, is the Degree of its Fluidity, or, if you please, its greater or lesser Im∣munity from Tenaciousness or Viscosity, which some Modern Philosophers (whose Opinion needs not here be discuss'd) think to belong to all Li∣quors as such. Now one may be the more inclin'd to expect a manifest Degree of Tenacity in the Spirit of Humane Blood, because among many Modern Chymists it passes for an Alcaly; and we know that divers other Alcalisate Liquors, as Oyl of Tartar per deliquium, Fix'd Nitre re∣solv'd

the same way, Solution of Pot-ashes, &c. are sensibly unctuous, and but languidly Fluid. But yet I did not observe, that some rectified Spi∣rit of Humane Blood, that I purpose∣ly try'd between my Fingers, did feel more unctuous than Common Wa∣ter. And whereas those that sell Brandy, or Spirit of Wine, are wont to shake it, till it afford some Froth, and then by the stay this makes on the Surface, to judge of the Tenacity or Tenuity of the Liquor, esteeming that to be the most Ʋnctuous, where∣on the Bubbles make the longest stay, and that the finest on which they soon∣est disappear; I thought fit by the same Method to examine Spirit of Humane Blood, and found that the Froth would last very little on the Surface of it, the bubbles breaking or vanishing, almost (if not quite) as nimbly, as if the Liquor had been good Spirit of Wine. And I likewise observ'd, that when I warily let fall some of our well rectify'd Spirit of

Blood upon some other body, it seemed to me, that the single drops were manifestly smaller than those of Water, and of several other Li∣quors, would have been, which will be much confirm'd by one passage of what I have to say about the third Quality referrable to the Consistence of the Spirit we treat of.

Because it may be a thing of some Importance, as well as Curiosity, to know how subtil the active parts of Spirit of Humane Blood are, and how disposed and fitted to disperse or dif∣fuse themselves through other Liquors of convenient Textures; to make a visible discovery of this, I bethought my self of a Method, that having formerly devised for several purposes, I thought fitly applicable to my pre∣sent Design. For having looked up∣on it as a great defect, that men have lazily contented themselves to say in general, that such a Body is of subtile, or of very subtile Parts, without trou∣bling themselves to find out any way

of making more particular and less indeterminate Estimates of that sub∣tilty; I was invited to find out and practise a way that might on divers oc∣casions somewhat supply that defect. But having delivered this easy method in another Paper, I shall forbear to repeat a tedious account of it in this; since it may here suffice to tell you in short, what will perhaps surprize you; namely, That according to the forementioned way, we so prepar'd Common Water by Infusions made in it without heat, that by putting one single drop of our rectified Spi∣rit of Humane Blood into ℥iv. + ℈iv. (which make 2000 grains) of the prepar'd Water, and lightly shaking the Vial, there appeared throughout the Liquor a manifest Colour, where∣of no degree at all was discernible in it just before. Which sufficiently argues a wonderful subtilty of Parts in the Spirit we employ'd; since that a single drop of it could disperse its Corpuscles, so as to diffuse it self

through, and mingle with two thou∣sand times as much Water, and yet retain so much Activity, as to make their presence not only sensible, but conspicuous, by a manifest change of Colour they produc'd. I confess this computation is made, upon sup∣position that a drop of Water weighs about a grain, and that a drop of our Spirit of Blood was of the same weight with a drop of Water.

The former supposition is com∣monly made; and though I have not found it to be exactly true, but that a drop of Water weigh'd a Tan∣tillum more than a Grain; yet that difference is much more than recom∣pens'd, by that which we found be∣tween the weight of a drop of Water, and the weight of one of Spirit of Humane Blood. For having in a very good and carefully adjusted Ballance, let fall ten drops of Com∣mon Water, and as many of our Rectified Spirit of Humane Blood, (as judging it a safer way to make

an Estimate, by comparing so ma∣ny drops of each Liquor than one alone;) we found, as we might well expect, that a drop of this last nam'd Liquor, as it was manifest∣ly lesser, so it was far lighter, than a drop of Water, in so much, that the whole ten drops did not a∣mount to four Grains. So that we may safely judge the drop of Spirit to have manifestly diffused it self, and acted upon above 4000 times so much Water in weight, (and per∣haps in bulk too) since indeed the pro∣portion extended a good way to∣wards that of one to 5000; and so may be said to be as that of one to between 4000 and 5000, which, tho it may seem incredible to those that are unacquainted with the great sub∣tilty of Nature and Art, in the Com∣minutions they can make of Bodies; yet I can by repeating the Experi∣ment easily convince a doubter, in less than a quarter of an hour. And this Subtilty of the Parts of Blood

will appear yet greater, if it be con∣sider'd, (what I think I can evince,) that no contemptible part of the single drop I employ'd was Phlegm, useless to the change produc'd, the operation being due to the Energy of the Saline Spirits of the little drop.