For the approximately quantitative determination of the benzene hydrocarbons, sulphuric acid of the specific gravity 1,6 is added to the reaction mixture. As a result of the increase of the specific gravity of the aqueous liquid, the oily nitro bodies rise to the surface and are brought into the graduated neck of the flask, when their volume can be measured. This volume is a direct indication of the benzene hydrocarbon content of the oil tested."

Marcusson1) has made a systematic investigation of the results produced by the addition of 10 p. c. of the several benzene hydrocarbons on the refraction of turpentine oil, also in how far this influence can be traced on the several fractions of such mixtures. Whereas with pure oils a slow increase in the refraction of the several fractions is observed, oils containing 10 p. c. of benzene compounds show a more or less marked drop. However, in the case of "solvent naptha" this is followed by a decided increase toward the end.

Carbon tetrachloride which, because of its high density, is added to conceal the addition of benzene, can, according to Marcusson be readily detected by means of the Beilstein copper test, also by the separation of potassium chloride when boiled with alcoholic potassa, and by fractionation. For its quantitative determination in the presence of turpentine oil and benzin, the chlorine content can be determined according to Carius' method. Pure carbon tetrachloride contains 92,2 p. c. Cl.

The adulteration of turpentine oil with copal oil has been observed by Vaubel2).

Production and commerce. So far as importance of production and the value of the product are concerned, the United States of America occupy the first position. This position is indicated by the following statistics:

1) Chem. Ztg. 33 (1909), 967.

2) Zeitschr. f. angew. Chem. 23 (1910), 1165.

Production for 1910 expressed in bbls. of 50 gallons (=abt. 190 1. or 165 kg.):

Export expressed in gallons:

According to the Forestry Bureau of the United States Department of Agriculture 2,300 000 acres of pine forests were used in 1890 for turpentine orcharding.

So far as production and export of turpentine oil forty years ago were concerned, North and South Carolina only came into consideration. The exhaustion of the trees in these states caused the industry to move farther southward. Thus Charleston, S. C, formerly an important port for export, no longer exports turpentine oil. The commerce in this article has drifted to Savannah and Brunswick in Georgia. In the world's commerce Savannah is the principal market for turpentine oil. Here is collected all the information concerning production, shipments from the interior, export and consumption. Here also is regulated the world's price (in cents per gallon) for turpentine oil. But even Savannah no longer exports fully one-half of all the oil, as it did 12 years ago, but only one-third. The cause lies in the fact that the forests of Georgia, which were regarded inexhaustible only a short time ago, are no longer affording the same yield. Hence the industry has moved still farther south and has acquired considerable dimensions in Florida and Alabama. Naturally the seaports of these states have entered into sharp competition with Savannah2). In recent years attempts have been made to utilize the well-nigh untouched pine forests of the western states, especially of Arizona, the national Bureau of Forestry having taken the first steps in this direction. In Mexico, private companies have likewise taken up the production of turpentine (See p. 81), but the industry is still in its infancy.

1) The fiscal year of the American turpentine industry begins April 1, and ends March 31.

2) According to the latest British consular reports, the export of turpentine products from Charleston has ceased completely since 1909. In Savannah, the amount of turpentine oil exported during the last three years has remained almost stationary, amounting to 5236774 gals. in 1909, with a value of $ 2629464; 4355122 gals, in 1910, with a value of $ 2760193; and 5221316 gals, in 1911, with a value of $3039232. Brunswick exported 245950 gals, in 1911, with a value of $119725. The exports from Pensa-cola, Fla., however, increased very materially, viz. from 1920723 gals, in 1910, with a value of £ 253100 to 4629519gals. in 1911, with a value of l 424976. The exports in 1909 were valued at £ 167085.

The principal European markets for American turpentine oil are London and Hamburg. Antwerp likewise imports considerable quantities.

Imports of turpentine oil in London, in Engl, tons @ 1016 kg.

Expressed in percentages:

Imports of turpentine oil in Hamburg, in barrels of 165 kg. (net)1).

Imports of Greek turpentine oil in Hamburg in iron drums with a net capacity of 400 to 600 kg.

German imports of American turpentine oil. The figures represent gallons.

Inasmuch as Western Germany is supplied with turpentine oil via Antwerp, and since some of the turpentine oil imported by England, no doubt, later finds its way to Germany, the above figures do not represent the total German importations.

From the official German import statistics it does not become apparent how much turpentine oil enters the German customs district since turpentine is entered with pine needle oil and rosin spirit under number 353a of the revenue tariff.

The value of American turpentine oil is fixed not merely by supply and demand, but is frequently influenced by speculation, hence the price varies considerably. More particularly in recent years the news as to the threatened exhaustion of the present areas of production, also the quarrels between the several combinations has caused fluctuations such as have not been recorded since the civil war.