to assume fermentations accompanied by the destruction of sugar and the formation of lactic acid, mannite, glucose, alcohol, acetic acid, and many other derivative bodies. This factitious juice, made up of sugar, water, and the juice of raw parsnips, presents a very near analogy to the juice of beetroots, from which sugar may be extracted-and offers no very remote resemblance to sugar-cane juice itself; many chemical 'properties of which liquids may be correctly studied on this factitious compound. If a portion of this compound saccharine juice be evaporated with all care, and with the view of effecting its crystallization, the labor will be in vain. Until some of the impurities, at least, are separated, no crystallization will ensue. If this factitious juice be a true practical representation of cane and other sugar-containing juices, it is quite evident, that the experiments cited have demonstrated the positive necessity of separating a considerable portion, at least, of the accompanying vegetable impurities, as a preliminary to obtaining the sugar in a crystalline form. Hence the following proposition is at once brought before us:-Given, a mixed solution, of sugar, water, and impurities-how practically to separate all but the sugar, with the least expense, and the least delay. This is the grand problem, upon the perfect solution of which every advance towards perfection in the manufacture of sugar hinges. As the usual agent employed in sugar-growing countries, for effecting this separation of impurities from raw sugar-containing juices-is lime, employed in some manner or other, it will be proper, in this place, to examine its agency on the factitious juice. If, then, a portion of the juice be admixed with a portion of lime, (rubbed with water into the condition of cream, for convenience of employment,) and then heated, the following changes will be seen to occur. When the heat has been pushed to the extent of 180° Fahr., a black crust of impurities will be seen to have collected on the surface of the juice, from which it may be skimmed off,-leaving the subnatant liquid comparatively clear and bright, but much deeper colored than it was originally. If this fluid, thus freed from the scum thrown up by the agency of lime, be now evaporated down to the proper degree, crystallization will be effected;-and substituting cane-juice for the factitious juice, here assumed to have been employed, the reader will have had brought before his notice the exact conditions of sugar boiling in the colonies. Although in the preceding experiment the scum might have been removed from the juice treated with lime, so soon as the temperature arrived at 180° Fahr.; although the subnatant liquor might then appear to the eye perfectly clear and bright-yet it is not difficult to prove, by many different kinds of evidence, that this brightness or clearness of the liquor is a most fallacious sign of its purity. The first evidence to this effect, is the very strong one, that fresh coats of scum continually arise as the evaporative process goes on a result which never happens in solutions of pure sugar and water. A second testimony to the same effect is afforded by the action of certain che mical tests, which are known to be endowed with the power of throwing down vegetable impurities. The acetates of lead are agents of this kind. Thus far, the agency of lime has been demonstrated to be defective; but the worst has yet to be told. Even conceding, for the sake of argument, that there is a certain theoretical relation between a definite amount of vegetable impurities and the quantity of lime necessary for effecting its removal (which is not the case), still this relation would vary for almost every sample of juice; and no amount of care, or talent, or appliances, could accomplish this exact apportionment. The manufacturer would, therefore, even under this assumption-the one most favorable to the employment of lime-be continually obliged either to choose between adding too little of that agent, or too much; actual neutralization by apportionment being amongst the most difficult of laboratory operations, and one totally impracticable on a large scale. A few remarks will be necessary here, relative to the assertion, that no theoretical relation does exist between the quantity of lime and the quantity of impurities to be separated. It will be intelligible when we consider that the removal of impurities effected by lime is not one of combination, but one of determination, and hence is influenced by such varying conditions of heat, density, solution, and other circumstances, that to calculate the chemical resultant of so many conflicting forces would be an impossibility. On this point the following may be taken as a practical exemplification. If a pint of cane-juice, under the proper conditions of temperature, be treated with ten grains of lime, a scum will form; which, if separated by filtration, or otherwise, a clear, though highcolored, fluid will result. If this fluid be now examined for lime, considerable quantities of it will be discovered by the proper chemical tests for that alkaline earth; a fact which might lead to the inference, if not checked by other observations, that more lime had been employed than was absolutely necessary for the separation of the impurities present. Nevertheless, it can be proved most unequivocally, by chemical tests (the acetates of lead, for example,) that not merely a large amount, but the greatest amount, of the original impurities still remains. This testing operation demonstrates, that there is not even a theoretical relation between the amount of impurities present, and the amount of lime most proper to effect their separation; because the agency of lime is indirect, not direct-because it does not effect any separation by combination, but by determination. To place this matter in the strongest point of view, the following case may be cited : If sixty-three parts by weight, exactly, of ordinary crystallized oxalic acid,* were to be dissolved in water, and if it were required * It is necessary to be precise in this expression. There are two substances known as crystallized oxalic acid, both of which are really combinations of oxalic acid with water. The ordinary crystallized oxalic acid is composed of one equivalent of real or dry oxalic acid, and three of water; and the other of only to separate the oxalic acid absolutely by means of lime, without employing more than the amount required of the latter agent, the problem would be solved with the greatest ease. Every tyro in chemistry knows, that for effecting this separation, twenty-eight parts by weight, exactly, of lime, would be the proper quantity; which being added, a solid and insoluble combination of the lime and the oxalic acid would result-would deposit; and the remaining liquid would be water absolutely pure. If the impurities which contaminate cane-juice, and other natural sugar-containing juices, assumed the tendency of forming a direct, invariable, and determinate power of combination with lime, an exact theoretical relation between the relative quantities of the two, necessary for effecting combination and separation, would exist; but as such theoretical relation is totally opposed to the actual conditions, the arguments founded upon the contrary assumption fall to the ground. If we cursorily pass in review the experiments detailed in this chapter, with the object of eliciting from them their legitimate deduction, we shall be led to the following important facts : -- That impure or crude sugar-containing juices refuse to crystallize, until a large portion of their accompanying impurities has been removed; that, moreover, such juices are very prone to undergo fermentation; hence the removal of such impurities is of the first importance. That lime will effect the removal of such an amount of the impurities as will admit of subsequent crystallization. That it is impossible to add lime in such a manner that some of this agent shall not remain. Hence, that even under the most favorable supposition-namely, that the use of lime has removed all impurities(which is not the case)-still, the resulting liquor will not be sugar and water, but a mixture of sugar, water and lime. But it has been demonstrated, that if a solution of sugar, water, and lime be boiled together, the sugar is rapidly destroyed. Hence, it follows, that lime, when used as a purifying or defecating agent for crude sugar-containing juices, is, under any circumstances, a most destructive agent, and that some better agent is a desideratum. It will have been clearly indicated, moreover, that any rational attempt to limit the injurious agency of lime, will be in the direction, not of primarily apportioning the amount of lime to be used, but of separating, by some agent not injurious to sugar, all excess of the agent which may remain in the cleared or defecated liquor. This, so far as I am aware, is an impossibility. Moreover, if there be ques one equivalent of real or dry acid, and one of water. Dry oxalic acid has never been obtained, although it may be caused to unite with certain bases, and thus be demonstrated to exist. In the experiment above cited, it exchanges its water for lime, with which it unites. The expression, dry crystallized oxalic acid, is absurd. * That is to say, in practice-on the small scale, and by the exercise of great care, lime may be separated with such exactitude, even by oxalic acid, that the sugar shall not be perceptibly injured. But a still better plan consists in the use of sulphurous acid, under circumstances which, having noticed in May, 1848, I caused to be printed in the summer of that year, and have subsequently taught in the laboratory. tion of separating any excess of defecating agent, the practical che mist will turn his attention to an agent of far greater efficacy, as a defecator, than lime-an agent which long since would have been employed in the sugar manufacture, if any means for separating it had been known. In detailing the prominent effect of the agency of lime on sugar solutions, both pure and mixed, I have purposely avoided all chemical remarks as to the rationale of this agency, from the conviction that they would little avail the practical sugar producer. In point of fact, the agencies thus brought into play are so multifarious, so complex, or so ill understood, that even a full recapitulation of all that is known on the subject would be of but little use. The general rationale of the agency of lime on pure solutions of sugar and water may be grasped by remembering that sugar is a body of acid reaction; hence, that it readily combines with bases; that under the agency of lime and heat it readily yields glucose, which substance is also possessed of an acid quality. Finally, that glucose, under the prolonged action of lime and heat, rapidly changes into glucic, melasinic, sacchulmic, and sacchumic acids, besides many other imperfectly known bodies. The action of lime and heat on the impurities existing in sugarcontaining juices, is referable to the property which albumen and several other organic bodies assume, of becoming to some degree insoluble, when they are exposed to incipient destruction. Thus, all that can be stated on this point amounts to the simple expression of the fact, that lime determines the separation of a certain amount of the impurities existing in crude sugar solutions. One important remark, however, relating to the use of lime as a defecatory agent, cannot be too strongly impressed upon the sugar grower. It is this that whatever the rationale of the employment of lime, in the sugar-boiling operation on raw juices may be, it is certainly not that, as is frequently stated, of neutralizing acidity. The term acidity is here to be understood in a general sense, as relating to such acids as the acetic and lactic. In strict chemical language, the term acid is extended even to sugar itself. Were there no greater necessity for using lime than this, it is clear that chalk would be a most efficient substitute; for whilst it would be equally potent with lime in neutralizing acidity, it could be employed in any quantity without fear of injury. The agency of lime on solutions of Muscovado, or other impure sugar and water, has purposely been omitted here, inasmuch as it will be discussed with the greatest propriety under the head of refining. It is well to remark, however, that there is no similarity between the kind of impurities existing in raw juices and those in colored sugars. The former chiefly consist of albuminous bodies natural to the juices; the latter of glucose, glucic, melasinic, sacchulmic and sacchumic acids, generated by the action of heat and lime on sugar. PROGRESS OF AMERICAN CITIES. 1.-CINCINNATI. WE are indebted to that valuable sheet, the Cincinnati Prices Current, for the following statistics of that rapidly growing emporium of the North-West. BUSINESS, 1849-50. The prospects were generally favorable for a season of prosperity at the commencement of the commercial year, which has just closed, and but for the failure of the wheat crop, in the central Western States in 1849, and the re-appearance of cholera during the present summer, the expectations then entertained would have been more than realized. But notwithstanding the serious drawbacks alluded to, business may be said to have been good throughout the year, and although trade could not at any time be said to be very active, yet the state of the markets was generally healthy, and the tendency of prices was such, that importers and jobbers, as well as produce merchants generally, realized fair profits on their general sales. There was but a comparatively small speculative business transacted in any of our leading staples, and most of the operations of the year having been characterized by prudence, the mercantile community have well sustained their credit; and while in the Eastern cities some heavy failures have taken place, we have had scarcely a stoppage to announce, and we may safely say that the new year is entered upon with unusually flattering prospects. GRAIN TRADE. In referring to the failure of the wheat crop, in the central Western States, in our last annual remarks, we stated that the crop would not much exceed onethird of an average yield. On referring to the receipts of flour at the several Western outlets, during the past year, we find that we were correct in our estimate, for although the receipts at this port and New-Orleans, show a deficiency of only about one-half, yet it must be recollected that the comparatively high prices current in the Western and Southern markets, attracted supplies from the Northern Lakes, which in ordinary years, found their outlet at New-York, and also, that there was a considerable stock of surplus wheat in the West, at the in-coming of the crops of 1849, while this season, the country was almost entirely bare when the new wheat was brought into market. In remarking on the prospect for prices, we stated that the full supplies in the Eastern markets, and the great falling off in the foreign demand, which we predicted would be experienced, would keep the market in check, and prevent prices from reaching the high point to which many, at the commencement of the year supposed, they would be carried. In the Western markets, however, flour commanded a higher price than we had supposed would be realized, and we find that the average price of the past year is $4 75, while that for 1848-9, was only $3 78. In the Eastern markets the range of prices was only about fifty cents per bbl. higher than last year, and frequently the rates current here were as high as those obtainable in New-York. In our remarks, relative to a probable falling off in the European demand for breadstuffs, we were entirely correct, as will be seen by the following figures, which show the amount exported from the United States to foreign ports, from Sept. 1, 1849, to about the 10th of August ultimo : It is seen that the United States contributed little to supply Great Britain with breadstuffs during the past year, and the facts show that we cannot expect any considerable demand from that country, while her own crops, and those of |