them into brick pug is largely increased, and then it is not so good, the plastic nature of the clay being less smooth and free than before.

Oxide of iron, lime, magnesia, potash, silica, bitumen, and fragments of rock are substances that impair the plasticity of clay, and they impress upon it certain characters that are of much importance to the manufacturer.

In England the process of brick-making is conducted somewhat differently from what it is in this country; and in the vicinity of London the principal supplies of brick-clays are obtained from the alluvial deposits lying above the London clay, the blue clay not being much used for brick-making. The material employed is a kind of gravelly loam, weak on the surface, and formerly gradually passing into either a strong clay or marl, or, as it is usually called, "malm," which is an earth suitable for making bricks, without any addition; but there is now but little natural malm to be had, as this class of clay is nearly exhausted. For making the best quality of bricks, which are called "malms," an artificial substitute is obtained by mixing together chalk and clay, previously reduced to a pulp in a wash-mill; this pulp is run off into shallow pits, where it remains until it has become of sufficient consistency for subsequent operations; but this process is resorted to for the best quality of bricks only, as the exis too great for the commoner kinds.

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The strong clay is not usually stony, and is generally worked without passing through the wash-mill, and the earth is mixed with chalk, reduced to the consistency of cream, which diminishes the contraction of the clay and

improves the gray color of the bricks; but the loams are usually so full of gravel that it is not possible to free them from stones without passing them through the wash-mill, and their texture is so open or loose, that a mixture of chalk is also necessary to bind the mass together, and to take up the excess of fusing silica in the process of burning.

Malming is not the only peculiarity of London brickmaking, as the bricks are not burned in kilns as with us, but are "clamped;" and, to make this effective, it is necessary to mix the fuel with the brick-earth so that each brick will contain the fuel necessary for its own vitrification, which fuel is domestic ashes, and they are collected in large heaps and sifted. The siftings which are called "soil," are thoroughly incorporated with the brick-earth in the process of soiling and tempering.

The cinders, or, as they are called, "breeze," are used as fuel to ignite the lower tiers of bricks, from which the heat gradually spreads over the whole of the clamp, and no spaces are left between the bricks, which are closely stacked, that the heat to which they are exposed may be as uniform as possible.

The usual proportions of breeze for every one hundred thousand bricks are about twelve chaldrons of cinders or breeze to light the clamp, and about thirty-five chaldrons of the sifted ashes or soil mixed with the brick-earth.

This manner of burning bricks should not be confounded with the process called "clamping" so common, and practised largely both in this country and in some parts of Great Britain remote from London, which is usually a method of

burning bricks by placing them in a temporary kiln, the walls of which are generally built of "green" or unburned bricks. The name of clamp is also applied to a pile of bricks arranged for burning in the usual way, and encased with a thin wall of burned bricks and daubed over with mud to retain the heat.

The London brick-makers obtain their supply of sand from the bottom of the river Thames, near Woolwich, where it is raised into boats used for that purpose, and the bricks made by these brick-makers are of the weakest kind, being much inferior in quality to those made by their predecessors from the middle of the fifteenth to the middle of the eighteenth century. The Dutch clinkers, or paving bricks, have for many centuries been of the hardest kind and of a superior quality, and are manufactured principally at Moor, a village about two miles from Gouda, in South Holland, the principal brick-fields being on the banks of the river Yessel, from which the chief material is derived. This is no other than the slime deposited by the river on its shores and at the bottom. The slime of the Haarlem Meer is also extensively used for this purpose, and the men who collect this in boats have long poles with a cutting circle of iron at the end, also a bag net with which they lug up the slime; and the hard paving bricks used for their streets are made with a mixture of this slime and sand.

Building bricks are made extensively at Utrecht, in the province of the same name, from the brick-clay which abounds in the vicinity.

The manner of taking material for brick-making from the

bottoms of rivers and lakes with poles is not of modern origin, as will appear from the inscription which once stood upon the brick pyramid of Howara, ten leagues from Cairo, for Herodotus cites the following inscription as at one time standing upon it, the translation reading: "Do not undervalue me by comparing me with pyramids of stone, for I am better than they, as Jove exceeds the other deities. I am made of bricks from clay, brought up from the bottom of the lake, adhering to poles."

Clay of a superior quality for brick-making abounds in nearly every portion of Russia, and although brick-kilns are scattered all over the empire, the total production for 1880 was only about 750,000,000, which quantity would not more than supply the demands of the city of London in a busy building year.

By reason of the country's great wealth of timber the production and consumption of bricks are by no means in proportion to the population of Russia. Wooden buildings are the rule and those of brick construction the exception, nor do the disastrous and too constantly recurring fires, with their attendant train of misery and suffering, seem to have much effect in enlightening the people. But still some little progress is being made in the production of bricks in that country, as will appear from the increase in the number of works as well as greater rate of increase in value of products.

In 1867 the number of works was 2166; but in 1879 the number had increased 48.5 per cent., and was 3217, and employed 33,404 persons, which were about as many as were employed in any other two manufacturing indus

tries of Russia combined, the great mass of population being of course engaged in agriculture.

The value of the brick product in 1867 was 4,622,667 rubles, and in 1869 it was 9,740,822 rubles, or an increase of 117 per cent. in value. Excellent' china-clay or kaolin is found abundantly in the neighborhood of Gluchove in the government of Tchermigov.

In the northern part of France the clays are loamy and of a fair quality for brick-making; they are not deep, averaging only about two metres in depth, but they gradually improve in both quality and depth toward the southern portion. The Italian clays are of a superior quality for brickmaking; they are naturally plastic, and require no sanding. Cuban and South American clays are generally poor both as regards strength and color.

There are a number of brick-kilns around Maracaibo for the manufacture of bricks and tiles. Maracaibo is the capital of the sovereign State of Zulia, one of the independent States composing the republic of Venezuela. The city has over 30,000 inhabitants, and is the residence of the President of Zulia.

The tiles are used both for roofing and flooring. There are also potteries for water-jars and earthen-ware pots; but the supply is not at all equal to the demand, and large numbers are continually imported, chiefly from France. Contrary to the usual run of South American clays, that in the vicinity of Maracaibo, and in fact for a great area around it, is pronounced to be of an excellent quality for brick-making.