1. That salt of steel has no deobstruent or aperient virtue by any immediate action, that it can possibly have on the blood, or other animal fluids, as some have imagined; but that, on the contrary, it owes this quality to its _not entering the blood_, which it would otherwise coagulate, and to _its action on the solids alone_. 2. That in diseases proceeding from a laxity of the solids, great care ought to be taken to restore and invigorate the _primæ viæ_; since a medicine (and this we may presume not the only one) whose immediate action is confined to those parts, is yet found by experience to produce so salutary effects in such diseases. 3. That as this salt does not enter the blood, and consequently cannot be in danger of too much stimulating or constricting the vessels, on which it only acts by consent, it may, in small doses, be successfully used in many cases, where it has been imagined to be hurtful, particularly in consumptions of the lungs, so frequent and fatal in this island; which are commonly attended with too great a laxity of the _primæ viæ_, and of the solids in general, tho’ they seem more immediately to proceed from a laxity and weakness of the pulmonary vessels; in which circumstances it must be of the utmost consequence to restore the tone of those principal organs of chylification, the _primæ viæ_; as good chyle not only corrects the acrimony of the blood, which in the advanced stages of consumptions so much prevails, but likewise saves a great deal of labour, which the lungs (already too much oppressed) must otherwise undergo from a crude and ill-concocted chyle. Agreeably to this we find, in the _Essays Physical and Literary_ of Edinburgh[36], two well-vouched histories of patients far gone in consumptions, with the usual symptoms of pain in the breast, cough, gross spitting of fetid matter, difficulty of breathing, hectic fits, and morning sweats, perfectly cured in a few weeks, by the use of the Hartfell-Spaw near Moffat; which, contrary to what is observed in most natural chalybeat waters, contains a fixed vitriol of iron. These, Sir, are the few observations I had to make at present on this subject. I have taken the liberty to address them to you, in order, if you shall think proper, to be communicated to your illustrious Society; which, I hope, will continue to latest posterity those interesting researches for the advancement of every branch of natural knowlege, by which it has already acquired so much and so deserved honour; and am, with the greatest respect, SIR, Your most obedient humble Servant, Edward Wright. Strand, Feb. 28. 1758. LXXX. _A Dissertation on the Antiquity of Glass in Windows. In a Letter to the Rev._ Tho. Birch, _D. D. Secret. R. S. By the Rev._ John Nixon, _M. A. F.R.S._ [Read Mar. 2, 1758.] London, March 2. 1758. Dear Sir,