PROCESS OF MANUFACTURE.

The process of manufacturing is as follows:

The bitterns are concentrated to 35° to 45° B. The stills are then filled to the funnel (see drawing), and sulphuric acid equivalent to the bromine present is added through the funnel (D). The contents of the still are then heated by turning on the steam at the bottom. Binoxide of manganese is now added in small amounts through the funnel for that purpose. This funnel extends some distance into the contents of the still. The bromine is liberated as a gas, and condensed in the leaden pipes as it goes through the condenser. The glass jar collects the bromine as a liquid. A slight excess of chlorine is liberated in the process, which will not condense. To provide for this, and also a small amount of bromine that does not readily condense, a return pipe leads from the jars again through the condenser, and into a second jar. This jar collects the remaining bromine. From this jar, a pipe leads to a charcoal tower (a couple of lengths of sewer pipe filled with charcoal and wet with bitter water) which absorbs the chlorine liberated in excess, and which would otherwise escape into the air and poison the workmen. Chlorate of potash is sometimes used instead of binoxide of manganese.. The proportions of manganese to sulphuric acid are as one to two (1 Mn O2 to 2 H, SO4). When chlorate of potassium is used, the proportions are one to four (1 KCl O3 to 4 H2 SO4). The refuse liquors from the bromine stills are utilized in the manufacture of chloride of calcium. The excess of acid present is neutralized with caustic lime and the liquors concentrated till the chloride of lime crystallizes out. A large amount of this product is manufactured annually at Pomeroy. Chloride of lime is an extremely deliquescent body, and is used extensively as a dryer in cellars and storehouses for preserving fruit, where a dry atmosphere is desired. It is also used as a high temperature bath in fruit canning establishments, melted chloride of lime boiling at 350° Fahrenheit. It is used also in the manufacture of artificial stone (Ransom's patent), and in the manufacture of ice in the south. It is an open question if these liquors could not be utilized in the manufacture of a commercial fertilizer of high value.

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THE STILL.

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The still is solid sandstone of the best quality. The walls are six inches thick. The cover is made separate, and luted to the base with beeswax. Two fire-clay funnels are set in the top, one for the introduction of sulphuric acid, the other for binoxide of manganese. A steam jet is inserted at the bottom for beating. The stears is blown directly into

the contents of the still. A second opening is made at the bottom for emptying the contents of the still after the bromine is extracted. The condenser is simply a wooden box into which cold water enters. The bromine condenses from vapor to a liquid in passing through. The extra bromine jar and charcoal tower have been already mentioned.

CHAPTER XIII.

NATURAL AND ARTIFICIAL CEMENTS.

BY PROFESSOR N. W. LORD, OHIO STATE UNIVERSITY.

Cements, as considered in this chapter, embrace those materials obtained by burning or calcining certain rocks or mixtures of clay and limestone, slag, etc., and which, when mixed with sand and water to a mortar, "set," or harden, without exposure to air. They all have lime as the basis of their composition, but the mortars they furnish differ from ordinary lime mortars in having less plasticity, as a rule, and in this property of hardening and not disintegrating under water. Cements are more and more replacing ordinary lime in the construction of all masonry where strength and durability are desired.

Even where lime mortar is used, as for ordinary brick-work, it is becoming customary to mix with it a certain proportion of cement. It is claimed by Gillmore, and other writers, that the cement so added is useless, but many excellent masons and contractors so use it, stating that it gives greater body to the mortar and prevents any settling of the interior of the work. The lighter-burned natural cements are used for this purpose, and, as many of these contain an excess of clay and magnesia, they possibly act upon the free lime in the mortar, hardening it in a way that the artificial cements would not do.

Cement rocks, after burning, do not "slack," or fall to powder when wet with water, but require to be ground in mills before using. They are thus distinguished from certain "hydraulic limes" which, after slacking in the usual way, furnish mortars setting under water more or less powerful. Magnesian limestones belong to this class. They slack slowly, developing little heat, and furnish mortars which are decidedly hydraulic. The magnesia, probably, acts by gradually crystallizing as a hydrate. As an experiment, a mortar was made of pure calcined magnesia and sand. In a few hours it set hard enough to be handled, and was put in water. It retained its shape, and while not getting very strong, it gradually hardened like a true cement. From this it would seem that in a magnesia lime mortar, this setting of the magnesia would account for the resistance to water, as it would prevent disintegration while the enclosed lime would gradually become carbonated and give strength.

Rocks which make cement by burning are very generally distributed, but, as a rule, the deposits are marked by great variability in quality. Of two layers in a quarry, one may be cement rock and the next a worthless shale; and even the same layer may, in a short distance, entirely change its character. From this cause, in part at least, the various attempts to work the smaller and more common deposits have more or less generally failed, and the natural cement of the market is obtained from only a few localities where large deposits of tolerably uniform rock occur. Of these, the two which furnish by far the larger part of the cement of the United States are Ulster county, New York, producing the Rosendale cements, and Louisville, Kentucky, from which are shipped the numerous brands of "Louisville cement. "

The rock is, in both places, a shaly limestone. In New York, it lies between the Lower Helderberg and Niagara groups; and in Kentucky, on top of the Corniferous limestone, corresponding exactly to the beds covering the limestone at Columbus, Ohio. The total production of natural cement in the United States in 1883 was estimated at 4,100,000 barrels of 300 pounds (Mineral Resources of the United States, Albert Williams, Jr.,) of which Ulster county, New York, furnished nearly one-half, and Louisville by far the larger part of the remainder.

Many of the impure limestones and shales of Ohio would furnish excellent cement when properly burned. Such are some of the magnesian limestones near Sandusky, a number of the Carboniferous limestones, the shales over and including top of the Corniferous. The Black (Huron) shale, where it lies over the limestone is, for the first fifteen or twenty feet, quite calcareous in some localities, and in such cases furnishes an excellent cement rock.

The efforts to make cement on a large scale from these various materials have not been very successful, probably from failure to understand the irregularity of the deposits and want of capital to duly press the enterprise. Works were started at Sandusky, but they did not continue. One of the most promising ventures in this direction was at Defiance, in the northwestern part of the state where Mr. E. H. Gleason manufactured the " Auglaize Cement" from the lower and most calcareous layers of the Huron shale. The cement was of excellent quality, and it is hard to account for the non-continuance of the works.

In the southeastern part of the state, cement has been, and still is, made at a number of points, the materials being the impure limestones of the Coal Measures. The cement used in the railroad bridge at Bellaire

was made by T. C. Parker & Sons, at Barnesville, Felmont county, from the cement limestone lying between the Pittsburgh and Meigs Creek coals (coals Nos. 8 and 9.) At Barnesville, the stone is five feet five inches thick, and was mined by drifting. These works are no longer in operation. The works just below Bellaire are now making cement from the same stone, which is drifted for in the hills. The stone is burned by mixing it with coal slack and running through a kiln. It is then ground in buhrs and barreled. Near New Lisbon, in Columbiana county, also, cement is made from a similar limestone which belongs to the Lower Freeport horizon. These are the only attempts that have been made to work the Ohio material on a commercial scale.

It thus appears that the rocks which yield cement on burning are invariably more or less impure, that is, silicious limestones, and in most cases strongly magnesian, though in some of the best foreign cements; this element is nearly absent. To illustrate this composition more fully, the following analyses are added, some of them made by the writer, and others gathered from various publications.

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