VOL. VI.] PHILOSOPHICAL TRANSACTIONS. 583 



one, to increase the materia tinctoria, and the other to fix, if possible, those 

 colours which we either have already, or shall hereafter discover for use- 

 As to the first, animals and vegetables, besides other natural bodies, may 

 abundantly furnish us. And in both these kinds some colours are apparent, as 

 the various colours of flowers, and the juices of fruits, &c. and the sanies of 

 animals ; others are latent, and discovered to us by the effects the several 

 families of salt and other things may have upon them. Concerning the ap- 

 parent colours of vegetables and animals, and the various effects of diff^erent 

 salts in changing them from one colour to another ; we have many instances 

 in Mr. Boyle. And if we might, with the permission of that honourable and 

 learned person, range them after our fashion, we should give you at least a 

 new prospect of them, and observe to you the conformity and agreement of 

 the effects of salt on the divers parts of vegetables : viz. 1. That acid salts ad- 

 vance the colours of flowers and berries, that is, according to the experiments 

 of Mr. Boyle, they make the infusions of balaustium or pomegranate flowers, 

 red roses, clove-gilly flowers, mezerion, pease bloom, violets, cyanus flowers, 

 of a fairer red; also the juices of the berries of ligustrum, of black cherries, 

 buckthorn berries, of a much fairer red : and to the same purpose acid salts 

 make no great alterations upon the white flowers of jessamin and snow drops. 

 0,. That urinous salts and alkalies, on the contrar}', quite alter and change the 

 colours of the same flowers now named, and the juices of the same berrie* 

 also, from red to green; even jessamin and snow drops. 3. Again, that in like 

 manner urinous spirits and alkalies advance, at least do not quite spoil the 

 colours of the juices of leaves of vegetables, of their wood and root. Thus 

 Mr. Boyle tells us, that urinous spirits and alkalies make the yellow infusions 

 of madder roots red ; of brazil wood, purplish ; of lignum nephriticum, blue ; 

 the red infusion of logwood, purple ; of the leaves of senna, red. 4. That, 

 on the contrary, acid salts quite alter and change the said infusions from red or 

 blue, to yellow. 



In the next place, we would note to you the effects of salts on animals in the 

 production and change of colours ; but the instances are very few or none that 

 I meet with in any author ; the purple fish being quite out of use, and cochi- 

 neal and kermes are by most questioned, whether they are animals or not ; 

 but, I think,^ we may confidently believe them both to be insects, that is, 

 worms or chrysalids of respective flies in proxima foetura. We find then, and 

 have tried concerning cochineal (which of itself is red,) that upon the affusion 

 of the oil of vitriol, that is, an acid salt, it strikes the most vivid crimson that 

 can be imagined ; and with urinous salts and alkalies, it will be again changeci 

 into an obscure colour between a violet and a purple. Pliny somewhere tells 



