_A curious Method of sealing a Letter, so as not to be opened, by variegating the Seal with different coloured Species of Wax._ Suppose you wish to have your seal of four colours, and that the cartrage of the escutcheon be _yellow_ or _or_, as well as the crown; the field of the shield or escutcheon, _red_ or _gules_; the seal itself _green_ or _synople_, and the supporters, if any, _black_ or _sable_. Take off then as many different impressions of your seal as you have kinds of wax to employ, taking care to make them on a very thin paper; this being done, with a pair of scissars cut out of each impression each of the objects that are to be variegated; that is to say, begin by cutting out the shield or escutcheon; and, by wetting it on the back with the tip of your tongue, place it on your seal over that part it represents; then do the same for the cartrage of the shield, as likewise for the supporters; and when all is well ranged, take the green wax, which is to represent the ground of the seal, and melt it as you usually do to seal a letter; then placing the seal on it that has in the mouldings the different objects which are to vary your seal, each of these objects will be found placed naturally, and will form a seal of four colours. If any body should attempt to break open the letter by heating the wax, the different colours in melting must mix and discover evidently the infidelity by their confusion. CHAP. XXVIII. _To make fine blue Wax, which is very difficult to be had._ Take an ounce of mountain blue, or blue ashes, an ounce of fine mastic, the fifth of an ounce of true Venice turpentine; then get a small iron pot or pan, well cleaned, and made so as to have a little spout or beak; put the mastic in it first, which is to be melted on the fire, taking care that it does not burn; then mix the turpentine with it: this mixture being done, take the pan from the fire and put the blue ashes in it; then stir it all well with a little stick: take care when you put in the blue ashes that the other ingredients are not too hot, as that would make the colour too black: when all is well mixed, and before it is quite cold, take two pieces of glass, which must be made wet with water; then pour on one of them this composition, in order to roll it in sticks under your fingers, which must be wet. In order to give this wax the necessary polish, pass the sticks over the flame of spirits of wine, which are to be lighted for this purpose. CHAP. XXIX. _A philosophical Mushroom._ Among the numerous and surprising phenomenons produced by different chymical proceedings, one of the most curious is certainly that of the inflammation of essential oils, by the mixture of nitrous acid. It is certainly astonishing to see a cold liquor take fire on pouring another cold liquor on it; such are the means by which one may form in three minutes the mushroom, called the philosophical mushroom.