The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

TITLE XIII. Of the Relation betwixt Spirit of Human Blood and the Air.

TO try whether the Air will have any con∣siderable effect on the Spirit of Human Blood after Distillation, as it evidently hath on the Blood before, I spread thinly upon a piece of white Paper some small filings of Cop∣per, and wetting them well without covering them quite over, with a few drops of Blood; by that means they being well exposed to the free Air; the Action of the Liquor was so much promoted, that within a minute or two it did even in the cold acquire a blueish co∣lour; and in fewer minutes than one would have expected, that colour was so heightned as to become Ceruleous; but another parcel of the same filings being put into a Vial, the in∣tercourse of the Air being excluded, the Li∣quor would not in some hours acquire so deep a colour.

Having in a clear Cylindrical Vial of about an Inch Diameter, put more filings of Cop∣per than was requisite to cover the bottom, and poured so much Spirit of Blood upon them as rought about a fingers breadth above them, it in a few hours acquired a rich colour, which after a day or two began to grow more faint, and afterwards gradually declined, till it was almost lost; yet the Liquor was not al∣together limpid or colourless, as I have often

had it with Spirit of Urine or Sal-Armoniack, and these remains of blueishness I attributed to the effects of the Air included in the Bottle, with so small a quantity of Liquor. And tho' I thought it not impossible, but that length of time might destroy it's blueishness, yet un∣stopping the Vessel, I observed, that in two minutes of an hour, the Surface of the Li∣quor where it touched the fresh Air became Ceruleous; and in a quarter of an hour the whole Body of the Liquor had attained a deep∣er colour than that of the sky, which colour grew sensibly paler again when the Vial was stopped: But one thing I must add is, that I have found the Experiment to succeed with some Analogy, when another Volatile Spirit hath been made use of, in which there was no Volatile Salt of Human Blood; but the Ex∣periment being repeated the Air produced a green and not a Ceruleous colour, which makes me suspend my Judgment till satisfied by further experience, whether the event of the former tryal depended on any Affinity of the Spirit with Blood or not. And here I shall add, that a parcel of Spirit of Human Blood being kept in Vacuo Byliano, when the Air was pumpt out, it afforded fewer and less bubbles than an equal quantity of common Water.