Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 264

With sulphuric acid thymol forms crystallisable colugated acid, the thymol sulphuric having the formula HC_{10}H_{13}SO_{4}. Undiluted thymol is an energetic caustic. According to Bucholz, thymol possesses ten times the septic power of carbolic acid, over which it also has the advantage of being non-poisonous, and of giving off an agreeable odour. Although considerably dearer than carbolic acid, the much smaller quant.i.ty required to produce an equivalent effect nearly equalises it in point of cost. It is said to have been successfully employed in the antiseptic treatment of wounds in destroying the ftor arising from ulcerated surfaces and carious bones; in the form of spray during surgical applications, as well as for certain throat affections, and as an ointment and lotion in psoriasis and other skin diseases. When thymol is to be used for lotions, injections, inhalations, or spray solutions, the Paris Pharmaceutical Society recommends 1 part of thymol to be dissolved in 4 parts of alcohol at 90, and this to be added to 995 parts of distilled water.

Dr Crocker, of University College Hospital, strongly recommends thymol lotion to be prepared with glycerin, which, he says, obviates the drying effect upon the skin produced by aqueous or spirituous solutions of the thymol alone. According to Mr Gerrard, this lotion is prepared by dissolving 1 part of thymol in 120 parts of glycerin, and reducing by water to 600 parts. Dr Symes says he finds milk to be an excellent solvent for thymol, of which it will take up readily to nearly 10 per cent. of its weight. In cases, therefore, in which solutions are required of greater strength than aqueous ones, he recommends the employment of the fluid.

An ointment varying in strength from 1 to 5 parts of thymol to 100 of lard, is said by Mr Gerrard to be employed in our hospitals. In the preparation of this ointment, it is of importance to first dissolve the thymol in a few drops of spirits, and then to mix it with the lard. The neglect of this precaution causes the undissolved particles of thymol present in the ointment to act as a caustic irritant on the skin, and to eat little holes in it. Mr Gerrard found vaseline an unsuitable and objectionable vehicle for the application of thymol, since, after a few days, an ointment prepared with it had its surface covered with minute crystals of thymol.

The 'Medical Times' contains the following formula for the preparation of thymol gauze for dressing wounds:--"Bleached gauze, 1000 parts; spermaceti, 500; resin, 50; thymol, 16 parts." This is said to yield an extremely soft and pliant preparation, excellently adapted for wounds, fitting accurately to them, and absorbing at the same time the blood and secretions from them like a sponge would do. Dr Ranke has pointed out that, in consequence of the great reduction in the amount of secretion from wounds caused by the use of thymol, the consequent consumption of bandages becomes so much less as to more than compensate for the great difference in price between thymol and carbolic acid.

Another advantage possessed by thymol over carbolic acid is that the redness, vesication, and eczema, frequently induced when dressings of the latter agent are used, does not follow the application of thymol dressings.

Mr Squire prepares an antiseptic adhesive plaster, containing 1 part of thymol to a 1000 of plaster.

Mr Gerrard in operating upon nine different samples of commercial oil of thyme (so-called oil of origanum) by means both of caustic soda and refrigeration, states, that except in one doubtful case, he was unable to obtain the slightest trace of thymol. From this circ.u.mstance Mr Gerrard infers that thymol is not present in the English oils of thyme of commerce, from which it must have been removed in the countries where it is produced, the residual cymene and thymene being sent us is an oil of thyme.

Large quant.i.ties of thymol are prepared in Germany, princ.i.p.ally from the seeds of the _Ptychotis ajowan_. One firm of chemical manufacturers residing in Leipzig is reported to have sent out during the months of September and November last year more than a ton of it. Thymol wadding is also in extensive demand.

=TIC DOULOUREUX'.= [Fr.] According to a writer in one of the medical periodicals, a solution of atropia, 2 gr., in water, 1 fl. dr., to which nitric acid, 1 drop (minim), has been previously added, applied as a paint, by means of a camel-hair pencil, to the part of the face over the spot affected, immediately and completely subdues the pain, or, at all events, within 3 to 5 minutes, in all accidental cases, and affords considerable relief in others. The application is to be continued until some relief is experienced. The solution, being very poisonous, must not be taken internally, nor applied to the skin when broken. See ATROPIA and NEURALGIA.

=TIN.= Sn. _Syn._ STANNUM (Ph. E. & D.), L. This metal has been known from the most remote antiquity, being mentioned in the books of Moses (Numb.

x.x.xi, 22), and by Homer ('Iliad,' x, 25), and other early writers. The ancients obtained it princ.i.p.ally, if not solely, from Cornwall. The Phnicians traded with England for this metal at least 1000 years before the birth of Christ.

Tin occurs in nature in the state of oxide, and, more rarely, as sulphide (TIN PYRITES). In Cornwall it is found under the form of peroxide (MINE-TIN, TIN-STONE), a.s.sociated with copper ore, in the slate and granite rocks, and as an alluvial deposit (STREAM-TIN) in the beds of rivers.

_Prep., &c._ The ore is first reduced to powder in stamping-mills, washed to remove earthy matter, and then roasted to expel a.r.s.enic and sulphur; it is next deoxidised or reduced by smelting it with about 1-6th of its weight of powdered culm, and a little slaked lime; it is, lastly, refined by 'liquation,' followed by a second smelting of the purer portion, which, after being treated in a state of fusion, for some time with billets of green wood, or 'tossed,' as the workmen call it, is allowed to settle, and is then cast into large blocks, which, after being a.s.sayed, receive the stamp of the duchy. Two varieties of commercial tin are known, called respectively grain tin and bar tin. The first is the best, and is prepared from the stream ore.

_Prop._ Tin approaches silver in whiteness and l.u.s.tre; in hardness it is intermediate between gold and lead; it is very malleable when pure, but the presence of a very small quant.i.ty of any other metal, particularly lead, deprives it of this property; when rubbed it evolves a peculiar odour, and when bent backwards and forwards it emits a peculiar crackling noise; it melts at 442 Fahr.; volatilises at a white heat; and when heated above its melting-point, with free access of air, is speedily converted into a yellowish-white powder, which is the peroxide, or the 'putty powder' of polishers. Sp. gr. 729 to 731.

_Pur._ It is almost entirely dissolved by hydrochloric acid, yielding a colourless solution; the precipitate thrown down by hydrate of pota.s.sium is white, and soluble in excess of the precipitant. If it contain a.r.s.enic, brownish-black flocks will be separated during the solution, and a.r.s.eniuretted hydrogen evolved, which may be inflamed and tested in the usual manner. The presence of other metals in tin may be detected by treating the hydrochloric solution with nitric acid, sp. gr. 116, first in the cold, and afterwards with heat, until all the tin is thrown down in the state of insoluble stannic oxide. The decanted acid solution from pure tin leaves no residuum on evaporation. If, after all the acid has been dissipated by heat, dilution with water occasion a heavy white precipitate, the sample contained bis.m.u.th; if, after dilution, a solution of sulphate of ammonium or of sodium produce a similar white precipitate (sulphate of lead), it contained lead; if ammonia, added in excess, occasion reddish-brown flocks, or if ferricyanide of pota.s.sium give a blue precipitate, it contained iron; and, if the clear supernatant liquid leave a residuum on evaporation, copper.

_Tests._ The stannous salts are characterised as follows:--1. Hydrate of pota.s.sium gives a bulky white precipitate, readily soluble in excess of the precipitant; on concentrating the solution, the precipitate is changed from stannous hydrate into stannic hydrate, which remains in solution, and metallic tin, which separates in brown flakes.--2. Ammonia, and the carbonates of pota.s.sium, sodium, and ammonium, give white precipitates, insoluble in excess.--3. Sulphuretted hydrogen gives, in neutral and acid solutions, a dark brown precipitate, which is soluble in hydrate of pota.s.sium, in the alkaline sulphides (especially when they contain an excess of sulphur), and in strong hot hydrochloric acid; and insoluble in nitric acid, even when boiling.--4. Sulphide of ammonium produces a like brown precipitate, soluble in excess of the precipitant, provided the latter contains an excess of sulphur.--5. Terchloride of gold gives, in the cold, on the addition of a little nitric acid, a precipitate of the purple of Ca.s.sius.--6. Mercuric chloride gives a black precipitate, but in excess it produces a white one.

=Stannous Chloride.= SnCl_{2}. _Syn._ PROTOCHLORIDE OF TIN. _Prep._ (ANHYDROUS.) Distil a mixture of tin and mercuric chloride. Grey, resin-like, solid, fusible, and volatile.

(HYDRATED; TIN SALT.) Boil an excess of tin in hydrochloric acid. A powerful deoxidising agent. It is somewhat extensively used as a mordant in dyeing.

=Stannous Hydrate.= Sn(HO)_{2}. _Syn._ HYDRATED OXIDE OF TIN. _Prep._ Precipitate stannous chloride with carbonate of pota.s.sium, well wash, and dry under 196. Greyish-white powder, soluble in acids and alkaline hydrates, except ammonia.

=Stannous Iodide.= SnI_{2}. _Syn._ PROTIODIDE OF TIN. Heat tin and iodine together. A fusible brownish-red, translucent substance, soluble in water.

=Stannous Oxide.= SnO. _Syn._ PROTOXIDE OF TIN. _Prep._ Ignite the hydrate in an atmosphere of carbonic anhydride. Black powder, inflammable in air, and insoluble in acids.

=Stannous Sulphide.= SnS. _Syn._ PROTOSULPHIDE OF TIN. A brittle bluish-grey substance, obtained by heating tin and sulphur.

The stannous salts behave with reagents as follows:--1. Hydrate of pota.s.sium, ammonia and alkaline carbonates, give a white precipitate, which is freely soluble in an excess of hydrate of pota.s.sium and in acids, sparingly soluble in excess of ammonia, only very slightly soluble in excess of carbonate of pota.s.sium, and insoluble in excess of carbonate of ammonium.--2. Sulphuretted hydrogen gives, in acid neutral solutions, a golden-yellow precipitate, either at once or on heating the liquid, which is readily soluble in pure hydrate of pota.s.sium, the alkaline sulphides, and boiling hydrochloric acid; less soluble in ammonia, and insoluble in nitric acid.--3. A plate of metallic zinc throws down metallic tin, under the form of grey scales or a spongy ma.s.s, from solutions free from nitric acid; and from those containing free nitric acid, white stannic hydrate.--4. Mercuric chloride gives a white precipitate.--5. Ferrocyanide of pota.s.sium gives no precipitate at first, but after a time the whole forms a thick jelly.

_a.s.say._ Each grain of stannic oxide (see _above_), after being washed and gently ignited, is equivalent to 78365 gr. of pure tin. The loss of weight represents the impurities. Each gr. of sulphate of lead, so treated, is equiv. to 683 gr. of metallic lead (nearly).

_Uses._ The uses of tin in the arts are well known. In medicine, 1 to 3 dr. of the filings or powder, made into an electuary with treacle, are sometimes given in tapeworm, for 2 or 3 successive mornings, followed by an aperient.

=Stannic Chloride.= SnCl_{4}. _Syn._ BICHLORIDE OF TIN, TETRACHLORIDE OF TIN, PERCHLORIDE OF TIN, PERMURIATE OF T.; STANNI BICHLORIDUM, STANNI PERMURAS, L. _Prep._ 1. (Liebig.) By dissolving grain tin in a mixture of hydrochloric acid, 2 parts; nitric acid and water, of each 1 part (all by volume); observing to add the tin by degrees, and to allow one portion to dissolve before adding another, as without this precaution the action is apt to become violent, and stannic oxide of tin to be deposited.

2. (ANHYDROUS; LIBAVIUS'S FUMING LIQUOR.) By heating stannous chloride in chlorine gas; or, by distilling a mixture of powdered tin, 1 part, with corrosive sublimate, 3 parts (5 parts--Fownes). A very volatile, colourless, mobile liquid, which fumes in the air, and boils at 248 Fahr.; when mixed with 1-3rd of its weight of water, it solidifies to a crystalline ma.s.s.

_Obs._ Solution of stannic chloride is much used by dyers, under the names of 'SPIRITS OF TIN,' 'DYERS' SPIRITS,' 'TIN MORDANT,' &c., the proportions of the ingredients and the state of dilution being various, according to circ.u.mstances or the caprice of the manufacturer. A process, which has been highly recommended, and which seems preferable to all others, is to prepare a simple solution of the stannous chloride, and to convert it into a solution of the stannic chloride, either by the addition of nitric acid and a gentle heat, or by pa.s.sing chlorine through it. See TIN MORDANTS.

=Stannic Hydrate.= Sn(HO)_{4}. _Syn._ HYDRATED PEROXIDE OF TIN, STANNIC ACID. _Prep._ By adding hydrate of pota.s.sium or an alkaline carbonate to a solution of stannic chloride. Soluble in acids and pure alkalies. Its compound with the latter are sometimes called STANNATES.

=Stannic Iodide.= SnI_{4}. By dissolving stannic hydrate in hydriodic acid. Yellow, silky crystals.

=Stannic Oxide.= SnO_{2}. _Syn._ BINOXIDE OF TIN, PEROXIDE OF TIN. _Prep._ By the action of nitric acid on metallic tin, the resulting white powder being well washed with water; or, by heating metallic tin above its melting-point, in the air. Yellow; anhydrous; insoluble.

_Obs._ Fremy has given the name of METASTANNIC ACID to the oxide prepared by the action of nitric acid on metallic tin; the hydrate he calls STANNIC ACID. See POLISHERS' PUTTY.

=Stannic Sulphide.= SnS_{2}. _Syn._ BISULPHIDE OF TIN, BRONZE POWDER, MOSAIC GOLD; AURUM MUSIVUM, AURUM MOSAIc.u.m, STANNI BISULPHURETEM, L.

_Prep._ 1. To pure tin, 12 oz., melted by a gentle heat, add of mercury, 6 oz.; to the powdered ma.s.s, when cold, add of chloride of ammonium, 6 oz.; flowers of sulphur, 7 oz; and after thorough admixture place the compound in a gla.s.s flask or matra.s.s, and gradually heat it, imbedded in sand, to low redness, and continue the heat for several hours, or until white fumes cease to be disengaged; the 'aurum musivum' remains at the bottom of the vessel, under the form of soft and very brilliant gold-coloured flakes.

2. (Berzelius.) Stannic oxide and sulphur, of each 2 parts; chloride of ammonium, 1 part; mix, and expose it to a low red heat, in a gla.s.s or earthenware retort, until sulphurous fumes cease to be evolved.

Used as a metallic gold colour, or subst.i.tute for powdered gold, in bronzes, varnish work, sealing-wax, &c.

=TIN FI'LINGS.= See TIN POWDER (_below_).

=TINFOIL, Lead in.= Tinfoil very rarely consists of pure tin; generally it contains more or less lead. According to the recent a.n.a.lysis of August Vogel, who has examined a great number of samples from very different sources, it contains from 1 to 19 per cent. of lead. There are, however, specimens of tinfoil which contain so little lead that it hardly gives a reaction with the appropriate tests.

Since tinfoil is so much used for covering articles of diet, or of confectionery, or of perfumery, it was a matter of some interest to determine whether or not there was any danger of transference of lead from the wrapper to the contents. A number of experiments upon soap, chocolate, and different kinds of dry sugar, which had been enveloped in tinfoil very highly charged with lead, showed that there was no contamination with lead. Cheese, on the other hand, on account of its being moist, and being closely in contact with the foil, did take up lead.

Of course the lactic acid of the cheese would also favour the taking up of the metal. A point worthy of being recorded in connection with this matter is the rapid diminution of the lead toward the centre of the cheese. Often plenty of lead was found in the rind, and none a little way in the cheese.[233]

[Footnote 233: 'Repertorium fur Pharmacie,' Von Buchnee.]

=TIN GLa.s.s.= See BIs.m.u.tH.

=TIN MOR'DANTS.= _Syn._ DYERS' SPIRIT, SOLUTION OF TIN, SPIRIT OF T., NITROMURIATE OF T. These, as noticed above, vary greatly in their composition and character.

_Prep._ 1. Take of aquafortis, 8 parts; sal ammoniac or common salt, 1 part; dissolve, and add, very gradually, of grain tin, 1 part; and, when dissolved, preserve it in stoppered bottles from the air. This is the common 'SPIRIT OF TIN' of the dyers.

2. (Berthollet.) Nitric acid, at 30 Baume, 8 parts; sal ammoniac, 1 part; dissolve, then add by degrees, of tin, 1 part; and when dissolved, dilute the solution with 1-4th of its weight of water.

3. (Dambourney.) Hydrochloric acid, at 17 Baume, 4 parts; nitric acid, at 30 Baume, 1 part; mix, and add by degrees, of Molucca tin, 1 part.

4. (h.e.l.lot.) Nitric acid and water, of each 1 lb.; sal ammoniac, 1 oz.; nitre, 1/2 oz.; dissolve, then add, by degrees, of granulated tin, 2 oz.

5. (Poerner.) Nitric acid and water, of each 1 lb.; sal ammoniac, 1-1/2 oz.; dissolve, then add, by very slow degrees, of pure tin. beaten into ribands, 2 oz.

6. (Schoeffer.) Nitric acid and water, of each 2 lbs.; sal ammoniac, 2 oz.; pure tin, 4-1/2 oz.; as last. All the above are used chiefly for dyeing scarlet, more particularly with cochineal.

7. (LAC SPIRIT.) From grain tin, 1 lb, slowly dissolved in hydrochloric acid (sp. gr. 119), 20 lbs. Recommended as a solvent for lac dye. For use, 3/4 to 1 lb. of the liquid is digested on each lb. of the dye for 5 or 6 hours, before adding it to the dye bath.

8. Hydrochloric acid, 6-3/4 lbs.; aquafortis, 1/2 lb.; grain tin, gradually added, 1 lb. Recommended for lac dye.