vapors of sulphurous acid which are disengaged. This can be accomplished by covering the agitator with a hood, which will conduct these suffocating vapors into a chimney-stack. The same arrangements for keeping the contents of the vessel warm, which were needed in treating heavy oil, are needed here. After half an hour's treatment, the heavy acid is drawn off at the bottom, a hot solution of soda-ley (five per cent. of a solution 12° Baumé) is added. The agitator is again put in motion, and the melted wax thoroughly treated, the soda-washing is withdrawn from the bottom of the tank which is kept warm, until it has completely settled and the contents are bright and clear. The wax is run into large flat cakes, which, when cool, have a fine pearly lustre, and are nearly colorless.

Decolorization through the agency of "bone-black" appears to offer the most perfect results. This process, however, is only employed upon paraffine which has been partially whitened either by repeated crystallization, or by the acid process, or by a combination of both processes. To accomplish this upon a manufacturing scale commensurate with the demand, a number of plans have been suggested. Perhaps the most complete of these is Ramdohr's filtering apparatus, which is constructed to filter about 2500 pounds per day. As it is inexpensively made and easily duplicated, it appears to supply the need. The following description is taken from Dingler's Polytechnic Journal.' The engravings which illustrate the machine are sufficiently clear without repeating here the whole article.

"This has the following peculiarities in its arrangement: 1. The mixing of the paraffine with bone-black does not take place by the hand or through a mechanical stirring contrivance, but through a warm current of air previously blown into the apparatus. 2. The paraffine treated with bone-black flows of itself into the filter paper placed in a glass funnel, and, after the influx has once been regulated, the operation proceeds without demanding special attention on the part of the workman. Even if, at times, less permeable paper should be accidentally placed in the filter, this, from the inattention on the part of the workman, cannot easily cause an overflow of the paraffine, while the greater or less permeability of the paper is easily observ

Fig. 36.

A

B

Ramdohr's Paraffine Filtering Apparatus.-Horizontal Section; A, Mixing Apparatus; B, Filtering Apparatus.

able during the first half hour, and the feed-cock should be adjusted accordingly by the workman. 3. The whole apparatus is heated by waste steam. 4. The mixing and filtering apparatus occupy little space. A, in Figs. 36 and

37, represents the mixing apparatus; B, in the same figs., the filtering apparatus. The steam first enters the filtering apparatus, and then passes through the mixing apparatus into the open air. The mixing apparatus consists of a

Fig. 37.

A

B

Ramdohr's Paraffine Filtering Apparatus.-Vertical Section; A, Mixing Apparatus; B, Filtering Apparatus.

wrought-iron chest with a turned cast-iron flange covered with iron cement, in which are three openings for the admission of three cast-iron mixing kettles. These kettles are fastened to the flange of the steam chest by a few screws in order to prevent any displacement which an insecurity

of the discharging vessel would cause. The kettles with the steam chest are rendered steam-tight in the simplest manner by a band of rubber placed beneath the rim of the kettle.

Ramdohr's Charcoal Pulverizing Drum or Cylinder.

A sufficient charge of partially refined paraffine is placed in the mixing tank, and, when thoroughly melted, from three to five per cent. of finely-granulated and freshly-burned animal-charcoal is added, and kept in suspension by a current of warm air passing through the pipe. The supply of melted wax passing to the filtering funnels is regulated by the large stop-cock nearest to the tank, and the quantity flowing into each funnel is adjusted by a separate and smaller stop-cock. The apparatus, which is said to do its work effectually, can be readily duplicated, and the capacity of the works indefinitely increased.

LUBRICATION AND LUBRICATING OILS.

The advantages, both pecuniary and beneficial, accruing to modern civilization, from the introduction of the heavy products of petroleum used for the lubrication of machinery,

are hardly second to those resulting from the introduction of the cheap and beautiful light furnished by its illuminating portion. It would be difficult to exaggerate its importance and value to the textile manufacturer, to the iron industry, and to the railroad interests. The hydro-carbon oils, for the purpose of lubrication, were at first received with but little favor, indeed, the opposition was all but universal. The disagreeable odor always associated with the imperfectly prepared oils first offered, disinclined superintendents of mills and factories to give them a trial even at prices much lower than those which they were accustomed to pay. Insurance companies on account of the explosive inflammable vapors, said to be inseparably connected with them, refused to take risks, except at greatly increased rates, upon factories where they were employed. The objections urged against their introduction were not wholly without foundation, and incited the manufacturers to increased diligence in removing them. Improved methods of treating these oils soon resulted in greatly improved products; the prolific yield of the crude material from the wells still further reduced their market price. Accurate methods of testing their real economic value were discovered and introduced into use, and thus through their real merit in the face of, often ignorant, opposition, these oils have made their way into general use and favor. It is not to be inferred from what has been said, that animal and vegetable lubricating oils are driven from the market, or are likely to be. They have distinctly important uses, and, whether alone, or combined with hydro-carbon oils, will still