222

SILK.

SAFETY LAMP. During a visit which I paid to Newcastle some time ago, 1took pains to learn the opinion of the hest judges of coal mining, upon the merits of thepatent invention of Upton and Roberts, described in the Dictionary , and I found fromthe concurring testimony of that very able engineer, Mr. Buddie, since lost to bisfriends and the world, and of Mr. Sopwith, well known for the geological study of thecoal formation, that the said lamp could not be safely used on account of its glass case,-wjSch, being most liable to break, would be apt to cut or rupture the meshes of thewjjf gauze within it, and thus to lay the flame open for explosions. It is not thereforein use.

SAGO. See Pehper in this Supplement.

SAL AMMONIAC. A patent wgs obtained in 1840, for improvements in the 1manufacture of this article, by Mr. H. Waterton. Two modes of operating are de-scribed ; the first consists in making a saturated solution of common salt in water, andmixing with it a quantity of finely pulverized carbonate of ammonia, about equal inweight to the salt contained in the solution. The mixture is agitated in a close vesselfor six or eight hours, and as much carbonic acid gas is infused therein as it will absorb(but the introduction of the gas is not absolutely necessary, although the patentee pre-fers it); the liquid is then separated from the solid matter, by filtration and pressure.The solid matter is chiefly bi-carbonate of soda, and the liquid holds in solution muriateand carbonate of ammonia, and common salt, and sometimes a small portion of the bi-carbonate of soda.

The liquid is now placed in a distilling vessel, and the carbonate of ammonia beingdistilled over into a suitable receiver, a solution of muriate of ammonia and common saltremains in the still. This solution is evaporated, by heat, to such a consistency as willcause the separation of the common salt, by crystallization, and the salt, thus crystallized,is evaporated from the liquid by any convenient method. The liquid is then evaporateduntil it attains the proper specific gravity for crystallizing, and it is transferred intosuitable utensils for that purpose. The crystals, produced by these means, are nearlypure muriate of ammonia, and, when pressed and dried, may be brought to marketwithout further preparation, or they may be sublimed into cake sal ammoniac.

The other mode of manufacturing sal ammoniac consists in taking a quantity ofliquid, containing ammonia, either in the caustic state, or combined with carbonic, hj"drosulphuric, or hydrocyanic acid (such as gas ammoniacal liquor, or bone ammoniacalliquor), and rectifying it, by distiliation, until the distilled portion containsfrom twentyto twenty-five per cent, of carbonate of ammonia. If the liquid contains any other acidsthan those above mentioned, ^sufficient quantity of lime is used in the distillation todecompose the ammoniacal salt.

The distilled liquid being now mixed with as large a quantity of powdered comm° nsalt as it will dissolve,- is agitated for several hours, and as much carbonic acid gas i 3infused into it as it will absorb. The remainder of the'operation is the same as befor®described in the first method of manufacturing sal ammoniac.— Newton’s .Journal, C.xxii. 35.

SEMOULE. The name given in France , and used in this country, to denote thelarge hard grains of wheat flour retained in the bolting machine after the fine flour hasbeen passed through its meshes. The best semoule is obtained from the wheat of thesouthern parts of Europe . With the semoule, the fine white Parisian bread called gru<t nis baked. Skilful millers contrive to produce a grqat proportion semoule from the large-grained wheat of Naples and Odessa. . .

SILK. Several pieces of silk were put into my hands, for analysis, on the 18th °t .February, after I had, on the preceding 12th of the month, visited the St. Katharine sDock warehouses, in New street, Bishopsgate street, for the- purpose of inspecting alarge package of the Corahs, per Colonist. I was convinced, by this inspection, that,notwithstanding the apparent pains bestowed upon the tin plate and teakwood packing*cases, certain fissures existed in them, through which the atmospheric air had foun^access, and had caused iron-mould spots upon the gunny wrapper, from the rusting 0oxidizement of the tinned iron. . ,

I commenced my course of analysis -upon some of the pieces which were mo^damaged, as I thought they were most likely .to lead me to an exact appreciationthe cause of the mischief; and I pursued the following general train of research :

1. The piece of silk, measuring from 6 to 7 yards, was freely exposed to the air,

weighed, afterward dried near a fire, and weighed again, in order to determineliygrometric property, or its quality of becoming damp by absorbing atmospheric vap ^Many of the pieces absorbed, in this way, from one tenth tq one eighth of their w ,weight; that is, from 1 oz to lj oz. upon 13 oz. This fact is very instructive, ^shows that the goods had been dressed in the'loom, or imbued subsequently, withvery deliquescent pasty matter.’ era -

2. I next subjected the piece to the action of distilled water, at a boiling te V