ally open, we have-1. United States; 2. Great Britain; 3. Germanic States; 4. France; 5. Belgium; 6. Russia; 7. Italy.

The following table is invaluable, for the means of comparison it affords:

Comparative view of the movement of the traffic on a portion of the Railways in operation in the United Kingdom, United States, Belgium, France and Germany.

*The average cost of the American railways, taken collectively, per mile, is only £8,129. Those to which the present Report refers include among them the most expensive in the states.

ART. VII.-MANUFACTURE OF SUGAR.

CRYSTALLIZATION OF SUGAR-CHEMICAL AND OTHER DOCTRINES OF SUGAR. The work which we now begin to republish, in parts, is from the pen of a distinguished English chemist, and is lately from the press, having not appeared in our country. The author, Dr. Scoffern, elaborates a new theory and process of sugar mauufacture, which will be invaluable to our planters. No work has yet appeared on the subject possessing higher merit.

Dr. Scoffern's attention was turned to colonial sugar manufacture in 1847, and he acknowledges the labors of Dr. Evans in the same field. In his own lan guage "I could not believe that there should exist any necessity for the loss of two-thirds of any material in producing, combined with a host of impurities, the remaining third-so opposed did the notion appear to any analogous case -so inconsistent with chemical harmony. I have since given the subject my almost undivided attention, and to prosecute it with the greatest efficiency, I have spent the greater portion of the subsequent period in a refinery," etc.-(ED.)

Inasmuch as the phenomena of crystallization are intimately associated with the production of sugar in the mercantile form, it has been considered desirable to offer a slight outline of that branch of science.

As a preliminary to a proper appreciation of the operation of that force, on which the formation of a crystal depends, it will be necessary to acquire a well-defined idea of the atomic and molecular constitution of matter.

Let it be assumed that matter, though immediately presented to our senses under the form of masses, is in reality but an aggregate of molecules; and that the latter are in their turn composed of particles of matter, which no human agency or law of nature, as nature now exists, can divide, and which, on account of this indivisibility, are called atoms.

The above-mentioned assumption is in accordance with all chemical testimony: not one valid experiment can be brought against it; so that the only proof necessary to establish the fact of the existence of these atoms is the direct visual proof of their existence-a proof which never can be attained, inasmuch as chemical experiment, of a kind to be universally assented to, has demonstrated that these atoms must be smaller than a certain determined bulk, in the contempla tion of which the human intellect is lost. Thus it can be demonstrated by the naked eye, that an atom of lead must be smaller than the billionth of a cubic line, how much smaller no one can tell, smaller, for aught we know, than there is space on the earth's surface for numerals to record. Yet, despite this inconceivable minuteness of atoms, the science of chemistry has been equal to the task of discovering their relative weights, and in many cases their relative bulks; has been able to demonstrate that the atom of oxygen weighs eight times as much as the atom of hydrogen, yet is only half the size; that an atom of lead weighs 104 times as much as one of hydrogen; of silver, 110; and so on for every elementary body, and the greater number of compound ones, of which the earth and its inha bitants are composed. The actual weight and actual size of these atoms, it is evident, must ever remain unknown, inasmuch as the means of measuring and weighing objects so inconceivably minute, involves an impossibility.

ever.

Much gratuitous difficulty has opposed itself to the contemplation of the atomic constitution of matter, by confounding two propositions, which are in themselves distinct-the proposition of the divisibility or non-divisibility of matter, with that of the divisibility or non-divisibility of space. To conceive space not to be infinitely divisible is irrational; but to conceive that matter filling such space is not infinitely indivisible, does violence to no reasoning process whatFor let it be granted that the matter filling such space is so hard and so coherent that no force now existent can cause its division or dismemberment-then we have an atom according to the definition, viz. a body which cannot be divided. Thus we learn that the term atom has no reference whatever to the smallness of a particle, but merely to the fact of its indivisibility; inasmuch, however, as practice demonstrates that the quality of indivisibility is alone confined to particles of incomprehensible smallness, this latter quality is always associated with the term atom.

Henceforth, then, the reader will assume the existence of atoms, and of aggregates of atoms, termed molecules; these molecules tending to unite again, and form masses.

It will be unnecessary for me here minutely to discuss the nature of those forces on which the formation of masses by the union of molecules depends. Suffice it to state, that these molecules are not only impressed with tendencies to combine, but to combine according to certain fixed and unvarying laws; as is best evinced by consideration of the fact, that, if the result of such combination be a solid, the latter has always a tendency to assume a definite geometrical form-to become, in fact, a crystal. Thus we may regard the crystalline condition the natural one of all solid bodies, and we may consider its absence due to the operation of some extraneous cause.

To illustrate the above proposition by immediate reference to sugar:- -The smallest possible molecule of sugar is composed of (C12 H10 O10) + Aq. What the form of such molecules may be, we cannot tell; but experiment demonstrates to us, that, when several of them combine to form a mass, their tendency is not to effect a compound of indeterminate or irregular form, but one possessed of well-defined, geometric boundaries; constituting a form which, although subject to slight variations, is always referable to the geometric figure called an oblique rhombic prism. Hence sugar is said by chemists to belong to the oblique prismatic system.

It is highly important to observe, that, although sugar crystallizes in certain well-defined geometric shapes, all referable to the oblique prismatic system, and therefore invariable, yet the size of those crys tals may be varied almost at the will of the operator; just as a bricklayer, with materials of the same form, may be conceived to build an oblique prism of any stated size. Nay, more, by a very easy modification of the treatment of two sugar solutions, both precisely equal in all respects, one shall be made to yield crystals, and the other a confused mass, devoid of all crystalline form, and hence called by chemists amorphous. A slight consideration of the operation of cohesive affinity between molecules will explain all that seems

difficult here; and, as the subject is somewhat recondite, perhaps an analogy from ordinary matters will not be devoid of value:-Suppose, then, a legion of soldiers standing in an ample space, and ordered by sudden word of command to form a square; it is clear that the element of time is necessary to the success of their evolution. Give them time enough, and the evolution will be made-the square will be formed. Give them less time, and the evolution will be incomplete; either no vestige of the square will be recognizable, or its formation will be imperfect. The former is the exact condition of sugar solutions which have been exposed to slow evapora tion; the latter the condition of such as have been exposed to a more rapid system of evaporation; and these remarks are applicable to all instances of crystallization whatever.

Thus we see, that, theoretically speaking, the process of effecting the crystallization of sugar should be entirely under the operator's control; and practice has rigidly demonstrated the correctness of the theory. Hence the sugar producer has certain well-known indications to follow out, provided he desire to obtain his staple in the form of crystals. He should evaporate by the slowest temperature consistent with economy of time and fuel, and thus retain his concentrated syrup in a fluid state, by the application of heat, until the crystals shall have accreted to the size desired.

In actual practice the sugar manufacturer is obliged to rely alone on the latter expedient, the process of slow evaporation being incompatible with the necessities of general commerce. The process would occupy too much time, and the result would necessarily be increased in price, without offering any adequate advantage. It would be, in fact, sugar candy, a material which is made by the process of slow evaporation here indicated, and which only differs from lump sugar in possessing larger crystals.

The principal bodies which come under the definition of sugars are Sugar of the Cane, of the Grape, of Milk, and of Manna. They have respectively the following compositions:

Of these the latter may be entirely dismissed from our consideration, and few remarks will suffice for all but the first.

ON SUGARS.-GENERAL REMARKS.

Cane-sugar is the only one which involves commercial interests on the large scale; being alone that which is employed in any considerable amount as a sweetening agent. For although manufactories of grape-sugar do exist on the continent, with the object of producing the material for admixture with such wines as are naturally deficient in it, and thus furnishing the means of supplying alcoholic strength,

yet the commercial interests involved are, comparatively speaking, small; and the clandestine manufacture of grape-sugar for the purpose of adulterating the West India staple, a manufacture which was extensively carried on in and near London, is without the precincts of any commercial speculation, in its true sense.

The sugar called Mannite is a mere chemical curiosity, and need not be farther adverted to in these pages, were it not for the circumstance that a portion of the juice of the cane is liable, under improper treatment, to be converted into this substance.

Sugar of milk is obtained, by a process unnecessary here to describe, from the whey of milk. Hence, in certain cheese-making localities, considerable portions of this substance are prepared. In some parts of Switzerland this is done, and the resulting sugar of milk is employed as a sweetening agent.

ON SUGARS-SPECIAL REMARKS.

Cane Sugar.-Under the definition sugar, the distinctive chemical characteristics of the substance have been so fully given, that nothing further in that respect need be stated here.

Henceforth I purpose devoting the term Sugar exclusively to sugar of the cane, appropriating the terms Mannite and Glucose to the sugar of manna and the sugar of grapes respectively.

Perhaps sugar, more than any other substance, has been mystified by a variety of appellatives. According to some it has been termed a salt by others an essential salt; whilst the conventional mode of using the terms saccharine matter and crystalline matter, as ap plied to sugar, terms now legalized by act of Parliament, imply that sugars may possess the former matter without the latter, the two being distinctively indicated as capable of existing separately, and as constituting, when united, the substance Sugar.

It seems unnecessary to point out how totally irreconcilable is the commercial and legislative definition of sugar, when compared with the chemical one.

Perhaps, however, the following parallel statement will place the discrepancy adverted to before the reader in its most powerful light:

CHEMICAL DOCTRINE OF SUGAR.

Sugar is a compound of Carbon, Hydrogen, and Oxygen, united in known, exact, and unvarying proportions.

Its taste is sweet; and inasmuch as taste depends on rapidity of solution in the mouth, and inasmuch as large crystals dissolve less rapidly than small ones, sugar imparts less sweetness for equal time in proportion as its crystals are large.

Size of a crystal is not defined by nature, but shape is defined. Sugars may be obtained in crystals of any size, may be even made to measure.

Sugar is not invariably alike, but different according to region, climate, or plant; may have more or less saccharine, more or less crystalline matter. Its smell, too, may vary; so may its taste, and also its color. Sugars may be weak or strong; beet-root sugar, for instance, is a weak sugar.

Weak sugars possess small grains (i. e., small crystals). Some weak sugars have large grains (i. e., crys tals): these are weak, because they do not sweeten well.