410 
Aurum musivum is one of the ingredients in making 
the imitations of the beautiful stones, Aranturine and 
Lapis Lazuli : though I think its place may be supplied 
by ground gold leaf. 
On the solution of Tin used as the composition for the 
Scarlet Dye, 
I shall have to treat on this dye when I come to the ar~ 
tide dying ; but the observations I have to make on tin 
and its solutions, may properly find place here. 
The usual composition, or mordant for the scarlet dye 
on woollen cloth is this. To one pound of the strongest 
aqua fortis add an equal measure of water in a glass ves- 
sel. Then bruise separately one ounce and a half of clean 
sal-ammoniac, and half an ounce of salt petre, and gradu- 
ally dissolve these in the diluted aqua fortis in a cool place. 
Then add by a small piece at a time from two ounces to 
two ounces and a half of grain tin, previously granulated 
by being melted, and poured through a bundle of twigs 
or a birch broom, into water. The solution ought to oc- 
cupy two days. 
The aqua fortis ought to be of the specific gravity 1,5 
or to weigh one half more than an equal bulk of water. 
Some good dyers, add only one ounce of sal-ammoniac, 
and two ounces of tin, to the pound of aqua fortis : but I 
shall prefer one ounce and a half of the salt, and two ozs. 
and a half of tin ; because there is some reason to be- 
lieve it will keep better. The sal-ammoniac prevents the 
oxydation of the tin. 
I shall have a good deal to say on the scarlet dye when 
I come to that article, but at present I confine my obser- 
vations, 1st To the tin. 2ly. To the acid. Sly. To 
the sal-ammoniac. 4ly. To the nitre. 51y. To the wa- 
ter. 
