This mixture, when rubbed too much, will be too fierce, and hardly show any stars; and, on the contrary, when not mixed enough, will be too weak, and throw out an obscure smoke, and lumps of dross, without any stars. The reason of this charge being called the spur fire is, because the sparks it yields have a great resemblance to the rowel of a spur, from whence it takes its name. As the beauty of this composition cannot be seen at so great a distance as brilliant fire, it has a better effect in a room than in the open air, and may be fired in a chamber without any danger; it is of so innocent a nature, that, although an improper phrase, it may be called a cold fire; and so extraordinary is the fire produced from this composition, that, if well made, the sparks will not burn a handkerchief when held in the midst of them; you may hold them in your hand while burning, with as much safety as a candle; and if you put your hand within a foot of the case, you will feel the sparks fall like drops of rain. _To make Touch Paper._ Dissolve in some spirits of wine or vinegar, a little saltpetre; then take some purple or blue paper, wet it with the above liquor, and when dry it will be fit for use. When you paste this paper on any of your works, take care that the paste does not touch that part which is to burn. The method of using this paper is, by cutting it into slips, long enough to go once round the mouth of the serpent, cracker, &c. When you paste on these slips, leave a little, above the mouth of the case, not pasted; then prime the case with meal-powder (see p. 165) and twist the paper to a point. _Of such Ingredients as show themselves in Sparks, when rammed into choked Cases._ The set colours of fire produced by sparks are divided into four sorts, viz., the black, white, grey, and red; the black charges are composed of two ingredients, which are meal-powder and charcoal; the white of three, viz., saltpetre, sulphur, and charcoal; the grey of four, viz., meal-powder, saltpetre, brimstone, and charcoal; and the red of three, viz., meal-powder, charcoal, and saw-dust. There are, besides these four regular or set charges, two others which are distinguished by the names of compound and brilliant charges; the compound charge being made of many ingredients, such as meal-powder, saltpetre, brimstone, charcoal, saw-dust, sea-coal, antimony, glass-dust, brass-dust, steel-filings, cast-iron, tanners' dust, &c., or any thing that will yield sparks; all which must be managed with discretion. The brilliant fires are composed of meal-powder, saltpetre, brimstone, and steel-dust; or with meal-powder, and steel-filings only. _Of the Method of mixing Compositions._