and which crystallized out on cooling, and after standing, in prisms or lengthened tables, similar to the compound of chloride of calcium and water. As these crystals had a peculiar smell from which they could not be freed by pressure between blotting paper, or by exposure to the air, and as they seemed less deliquescent than the ordinary crystallized salt with water, they were fused to determine the amount of volatile matter, in order to ascertain whether perhaps they were not a compound of amylic alcohol and chloride of calcium. The loss was 49.78 per cent., which corresponds to the chloride crystallized with six equivalents of water, or 49.28 per cent.

After having dehydrated the portions collected between 81°-110°; 110°-132°; and 132°-136°, which last contained the great bulk of the oil, they were submitted to four rectifications, in which the following stadia were observed:

81° 84°-90°-100°-110°-120°-129°-132°-136° Cent.

The residue above 136° was not sufficient to cover the thermometer. In the second rectification, 81°-84° was collected at 81°-820-84°. During the fourth rectification, the thermometer still continued to rise from 810-136°; but nearly the whole of the oil was collected at 132°— 136°, and the thermometer was longer stationary between 81°-84° than at any intermediate stadium. They all, where not masked by the odor of the fusel oil, (as in the case of the higher ones,) smelled strongly of turpentine. The distillate between 81° 84° was rectified, and what passed over at 81° collected. Its density at 19° was 0.8194; and it presented the characteristic of alcohol contaminated with some foreign substance. After having stood for a day over freshly ignited charcoal, water was added, in which it nearly all dissolved, giving a milky fluid, from which a little oil separated. Water was now shaken with the several distillates up to 81°-119° inclusive. The quantity of distillate was very much reduced by the water, and the resulting oil smelled strongly of turpentine. These oils, separated from the aqueous solution, stood over night upon charcoal, and were kept boiling for some time over fused chloride of calcium, so that the vapors flowed back into the flask; they were then distilled, in a wax bath, from the salt. The quantity of oil thus obtained was quite small. The chloride of calcium when dissolved in water, set free a small quantity of oil of turpentine which was mechanically mixed with it.

Since the portion of oils passing at 120°-129° was the greatest in quantity after those already mentioned, I was desirous of forming the double sulphate, in order to ascertain by that means the presence of another alcohol besides amylic. I had three-fourths of a fluid ounce at my disposal, to which was added gradually an equal weight of oil of vitriol. After having stood for a few hours, there were two layers on the addition of water; the upper one a yellowish green oil, which diminished on the addition of more water. What remained undissolved, was in too small quantity for further examination; when rectified over carbonate of potassa, it began to boil at 115°, the boiling point at once rising. When suffered to evaporate upon the hand, it gave the smell of amylic alcohol and turpentine. The double sulphuric acid thus formed was neutralized by pure carbonate of baryta, and the baryta double salt, after evaporation to

dryness in a water bath, was redissolved, filtered, and evaporated to crystallization. On cooling, crystals were obtained, which, under the microscope, and especially by polarized light, appeared as thin rhombic plates very much broken. I could not detect two different kinds of crystals. When dried for fifty hours in vacuo over sulphuric acid, these crystals presented the appearance of pearly scales, fatty to the touch. The mother waters gave a similar salt, and the mother water from these gave a small quantity of cauliflower-like crystals of the same appearance under the microscope; after having been dried in vacuo, their crystals blackened, and were decomposed when heated to 100° C.

The following is the amount of sulphate of baryta they contain, determined by incineration. They were difficult to burn, and after ignition they were moistened with a drop of sulphuric acid, and ignited a second time:

0-6105 gave BaOSO3 = 0·30325 = 49.67 per cent.
0.58525 "BaOSO 3
= 0.2895 = 49.47

66

Anhydrous sulpho-amylate of baryta contains 49-49 per cent. of sulphate of baryta.

Towards the close of this investigation, I met with Wurtz's paper on the occurrence of butylic alcohol in a fusel oil examined by him. I was therefore desirous of looking for this body in the fusel oil under examination. The oils left by adding water to the product, 81°-119°, after having been treated as described above, were in small quantity, and contained fusel oil, and oil of turpentine, besides a little water. They began to boil at a 105°, and were separated in two portions; those passing between 106-110°, and those above 110°. These two portions were treated with sulphuric acid, and the baryta salts formed. Of these, only the liquid passing at 106-110°, yielded enough for analysis, which was rendered uncertain by having unfortunately used for neutralization native carbonate of baryta which contained lime, and which was only discovered on examining the salts under the microscope, when the crystals of sulphate of lime were detected. The solutions were then evaporated to dryness, and exhausted with alcohol. The salts proceeding from the distillate above 110° yielded a small quantity of confusedly crystallized granules, not sufficient in quantity for analysis. The remaining portion gave a salt appearing in lance-shaped crystals under the microscope. The following is the analysis of the salt:

1st Crystallization.-0.184 gave 0·07875 BaOSO 3

21

66

43.21 per cent.

The mother waters yielded on concentration, 0.14675 of a salt which contained 0.06875 BaOSO

=

47.02 per cent.

Both of these sulphates of baryta contained a small portion of sulphate of lime. The following is the quantity of fixed sulphate in three of the vinic acids:

Sulpho-vinate,

S Lime
Baryta. Sulphate.

46.89

60.23

Sulpho-amylate, {Baryta.}
Lime

Lime

$39.31

Sulpho-butylate, {arma.Sulphate. {52-62

It appears most probable that the salts analyzed were sulpho-amylate of baryta with a little lime, and possibly mingled with sulpho-vinates. I

have not therefore been able to detect Wurtz's alcohol in the specimen of fusel oil for maize and rye. Different specimens of fusel oil appear to vary in the nature and quantity of their constituents. The specimen just examined contains but a very small quantity of the fatty acids.

Specification of a Patent granted to ALFRED VINCENT NEWTON, of Middlesex, for Improvements in the Manufacture of Lenses,-being a Communication.-Sealed 17th of April, enrolled October, 1852.*

The patentee commences his specification with the following explanatory remarks:-"The dioptric lens, heretofore and at the present time in use for sea-lights and for other lights requiring great intensity, being constructed of single zones or rings, made up of segments according to the diameter of the required lens, has induced a belief that glass could not be prepared without incurring the expense of grinding and polishing the curved surface; and that economy dictated a method of manufacture embracing a centre and zones or segments. The necessity daily shown for the more general application of a dioptric lens to the purpose of a sea-light, including, under that name, either revolving or stationary coast-light, baylight, bar-light, ship signal-light, deck and between deck-light, port-light, and all other lights for ships, tide-light, floating-light, and coast, harbor, and river-light generally; and also of a land-light-including, under that name, railway locomotive-light, carriage-light, ferry-light, and as applied to architectural puposes, and, in fact, to any purpose where an intensity of light is required-induced the inventor to examine the method of construction of the "built-up lens," with a view, at least, to reduce the expense without diminishing the strength of the light. Commencing with the suggestions of Buffon, that a spherical body, from its thickness, absorbs light in proportion to its density, and that a sectional figure, of any required shape and thickness, could be cast of vitrified material or glass, and ground in steps or concentric zones to produce a lens (as executed with partial success by the Abbé Rochon), the present inventor considered that, from the expense incidental to the accuracy required in grinding and polishing the steps or zones, the lens of Buffon was beyond the reach of the million. The experiments of the Abbé Rochon, however, were useful in preparing the way for the manufacture of the dioptric lens in separate pieces, which was subsequently accomplished by the ingenious Fresnel, after the suggestions of Condorcet, producing the lens known as the "annular band lens," at the present time in use in several lighthouses, and in which the spherical aberrations are nearly corrected, by making the foci of each zone to coincide. Although of great utility, the enormous expense of making the annular band lens of Fresnel, (in which not only each separate piece must have its surfaces formed with great accuracy, but all the several pieces must be fitted to each other, so that, when put together, they shall constitute a perfect whole,) has limited the use of this otherwise valuable and desirable invention to a very few localities.

The object of this invention is to produce a dioptric lens, which shall present all the practical advantages of the annular band lens of Fresnel, From the London Journal of Arts and Sciences, January, 1853.

and at so cheap a rate as to admit of its being applied to all purposes requiring intensity of light. And, to this end, the invention consists in a new manufacture of dioptric lenses, made in one or several pieces, moulded and pressed to the form required for the surfaces; and, when made in several pieces, the required fit of the several parts being produced by giving the reversed required form to the metal moulds in which the molten glass is to be put, and into and by which it is to be pressed.

Fig.L

Fig.2.

Fig.4.

Fig. 3

Fig. 1, represents, in vertical section, the apparatus employed for making a lens. a, is a circular mould, to receive the melted glass; b, is a follower, which rests on the mould; and c, is a plunger, that fits in the follower b, and is intended to spread the melted glass uniformly into the mould a, by pressure. This construction of mould, plunger, and follower, and the mode of using them, are well known to glass manufacturers. The mould may be made of any figure required; and the follower and plunger will be made to correspond with the mould. The mould a, instead of having the concentric central lens and rings, may present a plain surface; and the plunger c, may have on it the rings and figures shown in the mould a. The shape of the mould may be changed to any figure, whether convex or concave with the central zones or rings. The mould, instead of being made in one piece, may be made, sectionally, of as many separate rings or zones as there are designed to be rings or zones in the lens, or otherwise sectionally divided, according to convenience,—a suitable allowance in the diameter of each being made for the increased aggregate diameter, by reason of the parts being distinct; and, in such cases, the moulds for the separate rings and zones being laid together, and secured in their proper order, will form the entire mould; while the interstices, left between the separate pieces, will answer the same purpose as the holes at the angles of the zones, subsequently described, viz: to suffer the air to escape when the pressure is applied. If it should be desired (as it may be in the case of very large lights) to cast the lens itself in sections, the several sections may be moulded and pressed as described above, and then the whole cemented together in the usual way.

Fig. 2, shows, in perspective, a six-sided lantern; and fig. 3, is a transverse section of the same in the line 1, 2, of fig. 1. Each side of the lantern contains a lens, having a convex centre and several sections of zones or rings. This lens may be made in three pieces, d, e, f, which will require three separate moulds; or the whole may be cast together in one mould. Any required number of lenses may be combined together, after the manner shown at figs. 2 and 3. The cap g, of the lantern may vary in shape, and may be made of any suitable metal.

Fig. 4, is a vertical section of a hanging or hand-lantern, formed by fitting a stand, lamp, top, and ring, to a dioptric cylinder h, containing several zones or rings, of regular and irregular widths, which can be varied at pleasure, and may be manufactured of any length or circumference. If required, each lens may be made with one or many zones or concentric rings, according to the diameter,-the lens or segment of a lens being produced, as shown and described, by pressure in a mould, with or without "fire polishing." To promote focal intensity, and to prevent the absorption of light, it will be obvious that each lens should be manufactured as thin as the size and number of concavities and convexities will permit. It is not essential to lay down any rule for thickness, or for the size, as the intensity will be decreased by density; and therefore the thickness will be governed by the extent of surface required.

In the making of dioptric lenses, sharpness at the angles of the zones is of the utmost importance; and, to effect this object, it may be found necessary to form, in the angles of the mould, apertures (so small as to be nearly invisible to the naked eye) for the escape of air from the cavities of the mould; otherwise atmospheric air may be confined in such cavities: and, when pressure is applied, the air thus confined will prevent the glass from entering and assuming the required form of the sharp angles of the mould. When that part of the mould which forms the curved surfaces of the zones is made in sections, sufficient space can be left between the different zones for the escape of the air.

The patentee claims the manufacture of dioptric lenses of glass, in one or more pieces, by pressure in metallic moulds, substantially as specified.

On Soaps, and their Employment in Manufactures. By Professor F. C. CALVERT.*

It may perhaps be desirable that, before I enter into the technical details contained in this paper, I should give a short outline of the manufacture of soaps, and of their chemical composition. The manufacture of soaps may be ranged under two great heads, the one relating to soft soaps, and the other to hard soaps. Both soaps contain fatty matter; but in the former case it is combined chiefly with potash, in the latter with soda. There is also another important difference between these two classes of soap, for soft soaps contain all the substances which composed the fatty matter employed in their preparation, whilst in the soda soaps one of these substances is removed, namely, the oxide of glyceryle, or glycerine. Thus, in the manufacture of soft soaps, either the fatty matters nixed with a large proportion of fish-oil, or the fish-oil itself, are boiled with caustic ley; and when saponification is effected, and the whole sufficiently concentrated, it is allowed to cool; while in the case of hard soaps, the caustic leys employed contain a sufficient amount of water to dissolve the glycerine as it is removed from the fatty matters by the action of the alkali contained in the caustic ley. From these facts it may be seen that the chemical change which takes place consists in the substitution of oxide of potassium or sodium for the oxide of glyceryle existFrom the London Chemical Gazette, No. 250.