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ink, the quantity of galls cannot be much less than threetimes that of the vitriol; and that it cannot be muchgreater without somewhat injuring the ink in point ofblackness.

The proportion of liquid admits of much greater lati-tude, than that of the vitriol and galls to one another.One ounce of vitriol, three ounces of galls, and a hundredand fifty ounces of water, -made an ink, legible indeed,though greatly too pale. With a hundred ounces of wa-ter to the same quantity of galls and vitriol, the colourwas still too pale. With forty and fifty ounces of water,the ink was of sufficient blackness for common uses : butthe fullest and blackest colour of all was produced whenthe quantity of liquor was little more than enough tocover the powders, as six, eight, or ten ounces. It wasexpected that these small quantities of water, dissolvingall the vitriol, without being able to fully extract the vir-tue of the galls, and thus occasioning a deficiency in thequantity of astringent matter, would have yielded a perish-able ink. Nevertheless, characters written with thesemixtures have preserved their colour for fifteen years,continuing still sensibly blacker than where the menstru-um was in larger quantity. It appears therefore, thatthough a large portion of fluid may be tinged by thevitriol and galls of a blackness sufficient for many pur-poses, the using a little quantity is of advantage both tothe deepness and durability of the colour; perhaps onlyfrom the liquor being in this case more loaded with thecolouring matter of the ingredients, so that a greater bodyof colour is accumulated upon the stroke.

I next tried what alteration would result from the usingof different waters or other liquors for the menstruum.Distilled water, rain water, and hard spring water, em-ployed in the same proportions, had, so far as could be

D d d 2 judged.-