526

DYEING AND CALICO PRINTING.

One of the most useful of these mixtures may be made by taking the above-mentioned purple spirit, and adding to it i ounce of oxalic acid, previouslydissolved in hot water, for every gallon. This oxalate of tin will then servefor finishing royal blues, for putting a top bloom on blacks, as a scarlet spiritwith grain or lac, and as an orange spirit with mixtures of grain and flavin,young fustic, &c. If greater brightness is required, in case of scarlets orroyal blues, the proportion of oxalic acid may be raised from i ounce toi£ or 2 ounces per gallon. Such increase of oxalic acid is not recommendedfor topping blacks. This oxalate of tin makes the nearest approach to auniversal spirit for wool-dyeing.

The following are oxalates of tin all in adtual use :—

a. Muriate of tin, at 8o° Tw.6 gals.

Sulphuric acid, at 42 0 Tw.3 „

Oxalic acid .2 ounces per gallon.

b. Muriate of tin, at 76° Tw.6 gals.

Sulphuric acid, *at 42 0 Tw.4 „

Oxalic acid .2 ounces per gallon.

c. Muriate of tin, at 70° Tw.6 gals.

Sulphuric acid, at 40° Tw.4 „

Oxalic acid .2 ounces per gallon.

Claret Spirit.

The bluest shades are produced by a pure muriate of tin, made by mixing3 parts by measure of hydrochloric acid, at 32 0 Tw., with 1 part of water, andsaturating it with tin up to 48° to 50° Tw. If to be used in rag-dyeing, forthe conversion of blacks into clarets, 10 per cent of a solution of commonsalt in water, at 32 0 Tw., may be usefully added. The sulphuric acid whichthe rag-dyer uses will decompose the salt, forming sulphate of soda, while thehydrochloric acid liberated will aid in discharging the blacks. If redder orbrowner clarets are in request, there may be added to the muriate of tin fromj^th to T \jth by measure of dilute sulphuric acid, at 28° Tw.

The Chlorostannite of Ammonium, a compound of stannous chloride(protochloride of tin) and chloride of ammonium (sal-ammoniac), is preparedby heating tin-dust with sal-ammoniac. It forms regular odtahedral crystals,which dissolve in water, the solution becoming turbid on boiling. Its useshave been merely experimental.

The Stannite of Soda is a compound in which stannous oxide—the protoxideof tin—plays the part of an acid. It is formed by dissolving the precipitatedhydrate of stannous oxide in a solution of caustic soda to saturation, andpreserving the produdt, as far as possible, from contadt with the air. It is atpresent rarely used.

III. Sesqui-Salts of Tin.

The sesqui-salts of tin are much less used, and even much less known, thaneither the proto- or the per-salts. They may be distinguished by their colour,which is of a peculiar deep amber or brownish-yellow. At low temperaturesthey are moderately permanent, but at an ordinary summer heat they aredecomposed in about twenty-four hours. The best known compound of thisclass is—