VOL. LI.j PHILOSOPHICAL TRANSACTIONS. 429 



mers leave to make many observations on it, unless the weather proved favourable. 

 It passed the meridian about g. 



. XLf^. On the Vitriolic Waters of Amlwch, in the Isle of Anglesey, ivith occa- 

 sional Remarks on the Hartfell Spa, described in the 1st Vol. of the Edinburgh 

 Essays and Observations, and in the 4Qth Vol. of the Phil. Trans., and their 

 Comparison with other Waters of the same Class. By John Rutty, M. D. 

 Dated Dublin, Feb. 1 5th, 1750. p. 470. 



Amlwch is situated on Trasklwyn mountain, in the parish of Amlwch, in the 

 Isle of Anglesey, the water of which was sent to Dr. R. by Ambrose Lewis, of 

 Beaumorris, having been bottled May 31, 1757, and arrived in Dublin June 3. 

 It appears by the hydrometer to be as light as distilled water, notwithstanding 

 its strong impregnation. It is of a subacid taste, and very nauseously vitriolic ; 

 a lasting impression of that sort continuing in the throat giving suspicion of 

 copper, of which however it exhibits no evidence, by any degree of the hue of 

 that metal imparted to polished knives immersed in it, nor of sulphur, by dis- 

 colouring silver. It retained the above-mentioned taste, on being exposed se- 

 veral days in an open vessel ; quite otherwise than happens to our ordinary cha- 

 lybeates. It curdled with soap : it also curdled equal parts of milk, exhibiting a 

 pretty clear whey. With spirit of hartshorn, spirit of sal ammoniac, and the 

 solution of potashes, it exhibited ochreous and green grumes, as the martial 

 vitriol. 



Its appearances with galls, and other austeres, were very singular ; for tor- 

 mentil roots gave it only a dilute ink colour, soon fading; and green tea a dark 

 dun colour, on standing. It had not blackened the corks, except perhaps one 

 out of 6 ; and when the water was first poured out it struck no more than a 

 slightly bluish tincture with galls; which tincture, on standing all night, became 

 like a dilute ink ; but in a glass exposed 32 hours, the galls struck the dilute ink 

 colour sooner : and in some of the water, which he left exposed 4 days, and in 

 some of it, which he left in a phial corked, but only -f- full, 3 weeks, the effect 

 was very different; for to each portion of water so exposed, as before mentioned, 

 the galls imparted a most beautiful bright sky-blue; which blue tincture, a little 

 spirit of vitriol instantly destroyed. 



Hence may be seen the fallacy of trusting to a few appearances, and the danger 

 of rash conclusions, without repetitions of experiments and observations; which, 

 if they had been omitted, he had been led to conclude this water to be but 

 slightly impregnated with either a chalybeate or vitriolic principle; with which 

 last it is however assuredly strongly saturated, though the ordinary test with 

 galls does not discover it clearly by the blue tincture, until the dissolving acid is 

 partly exhaled. 



