with the same amount of linseed oil as would suffice to render the white lead thin enough to work well with the brush, as it is much lighter in weight.

One of its peculiarities, is the great affinity existing between its atoms for each other, it is so great that after the oil has decayed they will hang together into, a scale but never chalk off. In this respect it is the very opposite of white lead whose atoms we have seen have no affinity and which fall singly in what is known as chalking when the oil holding them together has decayed. But while this great adherence of its particles is good in some ways it has its faults too, in that when the oil has decayed instead of falling off single or chalking they hold together until they fall off as scales.

Zinc white therefore is a good corrective to combine with white lead for outside painting while the lead itself is a good corrective for the too great affinity of its own particles. The zinc preventing the chalking off of the lead and the lead its scaling propensities.

b. Zinc white is a very fine pigment to use in distemper, covering well and the tints made with it when used as a base are invariably cleaner and purer toned than those made with any other white as a base. The above also holds true for any tint made from it as a base with colors in oil.

It is invaluable for all enamelling work when ground in varnish. Some of the better kinds of French process made zinc whites are so very white in tone

that ordinary white lead shows a yellowish tone when placed side by side together.

Zinc white is the oxide of that metal and is made in two different ways-but by the same process of oxidation. These two methods are known as the "French" and as the "American." The zinc white made by the so called French process is manufactured from the metal, while that named American from the zinc ore instead.

THE FRENCH PROCESS.

C. Zinc white made by the French process is produced by placing metallic zinc in retorts or ovens where it is vaporized by heat-this vapor is conducted to upper chambers which are supplied with fresh atmospheric air for which the zinc has a great affinity in the state of vapor and with which it instantly combines when it comes in contact with it. From the ceilings of these chambers hang long sacks with their mouths opened and closely fitted together into which the floculent feathery oxide rises up and is caught up in these. The oxide which is caught the farthest away from the openings through which the zinc vapor arises from the retorts is the whitest and best-that which is caught nearest the openings usually containing more or less of foreign matter in the shape of dust, etc., which finds its way from the retorts into the chamber. This feathery mass is next subjected to a powerful compression when it is then ground up and packaged

ready for the market in a dry state or to be ground up in oil or varnish.

THE AMERICAN PROCESS.

d. The American process of making zinc white is essentially the same as that related for the French, differing from it only in the shape of the raw material. Instead of using the metallic zinc, zinc ore becomes the provider. That is placed in the retorts and vaporized in the same manner as related for the French process. However, as the ore contains so much more foreign matter and impurities the zinc white thus obtained is inferior in whiteness and quality to the first and is sold for less money than the other.

e. The name of French zinc has lost its significance as to being an index as to the source of supply of that article as today there is as good a quality of French process zinc made in America and which commands as good a price, as any zinc white imported from Europe.

In both the French and American zinc white the first and second qualities are designated as green and red seal respectively. The green denoting the best quality--the red the second.

THE EARTH WHITES.

70. a. Earth whites so called are all of mineral origin and according as they contain as a base either lime, clay, or sand are known as cretaceous, aluminous

or silicious. All possess somewhat different properties, each being better than any of the others for certain specific purposes.

b. Cretaceous earths are chiefly used in water colors and for that matter all earth whites are at their best in distemper and have that much in common, excepting when they are used in oils as adjuncts, correctives or adulterants for the metallic whites or any of the coloring pigments where each differ materially from the other.

The principal pigment with a cretaceous base is whiting or the carbonate of line, all others being simply variations of it more or less impure. Whiting is used in immense quantities as a base upon which to make the tints used in the printing of wall paper. As the main base in mixing tints for calcimine or in its self color, it reigns supreme and nearly all the ready prepared calcimine found on the market contain it as the main ingredient in their preparation. As an adjunct to graining colors in oil it is highly valued as it enables the grainer to reduce the strength of his colors so they can be thinned much more than would be possible but for the addition of the whiting.

The only other cretaceous pigment of value which differs from whiting materially is Gypsum or the sulphate of lime. It does not work quite so well as whiting in water colors and is seldom used as such without a special preparation which is patented and too intricate for use by the general painter. It is the base used

in all the so called anti-kalsomine paints patented preparations. It is too transparent in oil to be of any use as a self paint but is valuable in the preparation of Venetian red where it becomes its base. It is also useful as a corrective in many of the other colors and in the compounding of white paints.

There used to be a number of whites in the markets some years ago such as Spanish white, London and other fancy named whites, which were prepared from whiting and from which they differed only in the form given it of pyramidal drops or cakes.

C. The only pigment with an aluminous base is "China clay" which is worth mentioning. It possesses more body in oil than those of the preceding class and when well cleaned of foreign matter makes a good water color paint. On account of its body, if such may be called a semi-transparent muddy looking stuff in its self color in oil it is used as an adjunct and corrective in many white paints which come ready prepared but it is used most frequently as an adulterant.

d. The silicious whites are represented by the white silicate earths. Some are found that are of a clean white but most of them are generally off color. The white ones are used in the preparation of "English kalsomine" and used as used as water colors water colors but they are very inferior to whiting for such a purpose. Their greatest utility as pigments lays in the silicate earth's use as correctives to the white metallic pigments and as such also for several other colors. For such a pur