Chemical Composition—Pepper contains resin and essential oil, to the former of which its sharp pungent taste is due. The essential oil has more of the smell than of the taste of pepper.[2163] The drug yields from 1·6 to 2·2 per cent. of this volatile oil, which agrees with oil of turpentine in composition as well as in specific gravity and boiling point. We find it, in a column 50 mm. long, to deviate the ray of polarized light 1°·2 to 3°·4 to the left.
The most interesting constituent of pepper, Piperin, which pepper yields to the extent of 2 to 8 per cent., agrees in composition with the formula C₁₇H₁₉NO₃, like morphine. Piperin has no action on litmus paper; it is not capable of combining directly with an acid, yet unites with hydrochloric acid in the presence of mercuric and other metallic chlorides, forming crystallizable compounds. It is insoluble in water; when perfectly pure, its crystals are devoid of colour, taste and smell. Its alcoholic solution is without action on polarized light. Piperin may be resolved, as found by Anderson in 1850, into Piperic Acid, C₁₂H₁₀O₄, and Piperidine, C₅H₁₁N. The latter is a liquid colourless alkaloid, boiling at 106° C., having the odour of pepper and ammonia, and directly yielding crystallizable salts.
Besides these constituents, pepper also contains some fatty oil in the mesocarp. Of inorganic matter, it yields upon incineration from 4·1 to 5·7 per cent.
Commerce—Singapore is the great emporium for pepper, of which 197,478 peculs (26⅓ million lb.) were imported there in 1877. The largest part of it finds its way to England. The import of pepper into the United Kingdom during 1872, was 27,576,710 lb. valued at £753,970. Of this quantity, the Straits Settlements supplied 25,000,000 lb., and British India 256,000 lb. Of the quantity of 25,917,070 lb., imported in 1876 into Great Britain, the home consumption was 9 million lb.
The exports of pepper from the United Kingdom in 1872 amounted to 17,891,620 lb., the largest quantity being taken by Germany (5,201,574 lb.) Then follows Italy (2,288,647 lb.); and Russia, Holland and Spain, each of which took more than a million pounds.[2164]
The varieties of pepper quoted in price-currents are Malabar, Aleppee and Cochin, Penang, Singapore, Siam.
A large quantity is also shipped from Singapore to China, the imports of that country in 1877 of both black and white pepper, being 53,844 peculs (7,179,200 lb.)
Uses—Pepper is not of much importance as a medicine, and is rarely if ever prescribed, except indirectly as an ingredient of some preparation.
Adulteration—Whole pepper is not, we believe, liable in Europe to adulteration;[2165] but the case is widely different as regards the pulverized spice. Notwithstanding the enormous penalty of £100, to which the manufacturer, possessor, or seller of adulterated pepper is liable,[2166] and the low cost of the article, ground pepper has hitherto been frequently sophisticated by the addition of the starches of cereals and potatoes, of sago, mustard husks, linseed and capsicum. The admixture of these substances may for the most part be readily detected, after some practice, by the microscope.[2167]
White Pepper.