584 PHILOSOPHICAL TRANSACTIONS. [aNNO I67I. 



US, that the Gauls in his time could dye with vegetables, what the Romans 

 with SO much danger and pains sought for in the bottom of the sea. Indeed, 

 we find many plants mentioned by the same author, which either are not now 

 known to us, or at least neglected. 



We will now add some of our own considerations and trials. And first, con- 

 cerning the apparent colours in flowers, we think we may insert ; 1. That 

 generally all red, blue and white flowers are immediately, on the affusion of an 

 alkali, changed into a green colour, and then in a short time turned yellow. 

 2. That all the parts of vegetables, which are green, will in like manner strike 

 a yellow with an alkali. 3. That what flowers are already yellow, are not 

 much changed, if at all, by an alkali or urinous spirit. 4. The blue seed husks 

 of glastum sylvestre long gathered and dry, diluted with water, stain a blue 

 which upon the affusion of lye strikes a green, which green or blue being 

 touched with the oil of vitriol dyes a purple ; all these three colours stand. 

 5. On the tops of fungus tubulosus, so called by Mr. Ray in his late catalogue 

 of the plants of England, are certain red knots ; these upon the affusion of 

 lye, will strike a purple, and stand. 



As for the latent colours in vegetables and animals ; to be discovered to us 

 by the affusion of salts ; they likewise, no doubt, are very many. We will set 

 down only a few instances in both kinds, which have not been, that we know 

 of, discovered or taken notice of by others. Latent vegetable colours, i. The 

 milky juice of lactuca sylvestris costa spinosa, and sonchus asper et laevis, upon 

 the affusion of lye, will strike a vivid flame colour or crimson, and after some 

 time quite degenerate into a dirty yellow. 2. The milk of cataputia minor, 

 upon the affusion of lye, especially if it be drawn with a knife, and has at any 

 time stood upon the blade of it, will strike a pui-ple or blood red colour, and 

 bv and by change into an ignoble yellow. Latent animal dyes, i. The com- 

 mon hawthorn caterpillar will strike a purple or carnation with lye, and stand. 

 2. The heads of beetles and pismires, &c. will with lye strike the same car- 

 nation colour, and stand. 3. The amber-coloured scolopendra will give with 

 lye a most beautiful and pleasant azure or amethystine, and stand. 



Lastly, as to fixing of colours for use ; we may use the following obvious 

 inferences, 1 . That in all the instances above-mentioned, whether vegetable 

 or animal, there is not one colour truly fixed ; however there may, I conceive, 

 be some use made of them, as they are. I say truly fixed, that is, proof of salt 

 and fire ; for, what seem to stand and be lye proof, are either wholly destroyed 

 by a different salt, or changed into a much different; colour ; which must needs 

 prove a stain and blemish, when it shall happen in the use of any of them. 

 2. That both the apparent and latent colours of vegetables are fixable : an in- 



