27 to 4 per cent. of ash, consisting mainly of calcium carbonate, but containing also carbonates of potassium and magnesium. Phosphoric acid appears never to occur in gum.

Natural gum may therefore be regarded as a salt of arabic acid having a large excess of acid, or perhaps as a mixture of such salts of calcium, potassium and magnesium. It is to the presence of these bases, which are doubtless derived from the cell-wall from which the gum exuded, that gum owes its solubility.

It still remains unexplained why certain gums, not unprovided with mineral constituents, merely swell up in water without dissolving, thus materially differing from gum arabic. There is also a marked difference between gum arabic and many other varieties of gum or mucilage, which immediately form a plumbic compound if treated with neutral acetate of lead. The type of the swelling but not really soluble gums, is Bassora Gum1 (p. 156); but there are a great many other substances of the same class.2

Commerce-The recent imports of Gum Arabic into the United Kingdom have been as follows:

1871

76,136 cwt., value £250,088.

1872

42,837 cwt., value £123,080.

The country whence by far the largest supplies are shipped, is Egypt. Uses-Gum is employed in medicine rather as an adjuvant than as possessing any remedial powers of its own.

Substitutes-Feronia Gum. This is the produce of Feronia Elephantum Correa, a spiny tree, 50 to 60 feet high, of the order Aurantiacea, common throughout India from the hot valleys of the Himalaya to Ceylon, and also found in Java. There exudes from its bark, abundance of gum which appears not to be collected for exportation per se, but rather to be mixed indiscriminately with other gum, as that of Acacia.

Feronia gum sometimes forms small roundish transparent, almost colourless tears, more frequently stalactitic or knobby masses, of a brownish or reddish colour, more or less deep. In an authentic sample for which we are indebted to Dr. Thwaites of Ceylon, horn-shaped pieces about an inch thick and 2 inches long, also occur.

Dissolved in two parts of water, it affords an almost tasteless mucilage, of much greater viscosity than that of gum arabic made in the same proportions. The solution reddens litmus, and is precipitated like gum arabic by alcohol, oxalate of ammonium, alkaline silicates, perchloride of iron, but not by borax. Moreover, the solution of Feronia gum is precipitated by neutral acetate of lead or caustic baryta, but not by potash. If the solution is completely precipitated by neutral acetate of lead, the residual liquid will be found to contain a small quantity of a different gum, identical apparently with gum arabic, inasmuch as it is not thrown down by acetate of lead. If the lime is precipitated from the Feronia mucilage by oxalate of potassium, the gum partially loses its solubility and forms a turbid liquid.

From the preceding experiments, it follows that the larger portion of Feronia gum is by no means identical with gum arabic. The former

1 Guibourt, Hist. des Drogues, iii. (1850) 421.

For further information, see Wiesner,

Gummiarten, Harze u. Balsame, Erlangen, 1869; Flückiger, Pharm. Journ. x. (1869) 641.

when examined in a column of 50 mm. length, deviates the ray of polarized light 0°4 to the right,-not to the left as gum arabic. Gum arabic may be combined with oxide of lead; the compound (arabate of lead) contains 30-6 per cent. of oxide of lead, whereas the plumbic compound of Feronia gum, dried at 110° C., yielded us only 1476 per cent. of PbO. The formula,-€12HoPbO" + 3"H"O"; supposes 15 per cent. of oxide of lead.1 2[C12 421 0") Pb + 2(C22 422 0")

Feronia gum repeatedly treated with fuming nitric acid, produces abundant crystals of mucic acid. We found our sample of the gum to yield 17 per cent. of water, when dried at 110° C. It left 3.55 per cent. of ash.

CATECHU.

Catechu nigrum; Black Catechu, Pegu Catechu, Cutch, Terra Japonica; F. Cachou, Cachou brun ou noir; G. Catechu.

Botanical Origin-The trees from which this drug is manufactured are of two species, namely:

1. Acacia Catechu Willd. (Mimosa Catechu L. fil., M. Sundra Roxb.2), a tree 30 to 40 feet high, with a short, not very straight trunk 4 to 6 feet in girth, straggling thorny branches, light feathery foliage, and dark grey or brown bark, reddish and fibrous internally.

It is common in most parts of India and Burma, where it is highly valued for its wood which is used for posts and for various domestic purposes, as well as for making catechu and charcoal, while the astringent bark serves for tanning. It also grows in the hotter and drier parts of Ceylon. A. Catechu abounds in the forests of Tropical Eastern Africa; it is found in the Soudan, Sennaar, Abyssinia, the Noer country, and Mozambique, but in none of these regions is any astringent extract manufactured from its wood.

2. A. Suma Kurz3 (Mimosa Suma Roxb.), a large tree with white bark, nearly related to the preceding but not having so extensive a geographical range. It grows in the South of India (Mysore), Bengal, and Guzerat. The bark is used in tanning, and catechu is made from the heart-wood.

The extract of the wood of these two species of Acacia is Catechu in the true and original sense of the word, a substance not to be confounded with Gambier, which though very similar in composition, is widely diverse in botanical origin, and always regarded in commerce as a distinct article.

History-Barbosa in his description of the East Indies in 15141 mentions a drug called Cacho as an article of export from Cambay to Malacca. This is the name for Catechu in some of the languages of Southern India.5

About fifty years later, Garcia d'Orta gave a particular account of

1 We obtained 14.56 and 14.96 per cent. of PbO.-Pb = 207.

2 Some Indian botanists, as Beddome, regard Mimosa (Acacia) Sundra as distinct from A. Catechu.

3 Brandis, Forest Flora of North-Western and Central India, Lond. 1874. 187, from

which excellent work we also borrow the description of A. Catechu.

Published by the Hakluyt Society, Lond. 1866. p. 191.

5 As Tamil and Canarese, in which according to modern spelling the word is written Káshu or Káchu.-Moodeen Sheriff, Suppl. to Pharmacopoeia of India, 1869. 96.

the same drug1 under its Hindustani name of Kat, first describing the tree and then the method of preparing an extract from its wood. This latter substance was at that period made up with the flour of a cereal (Eleusine coracana Gärtn.) into tablets or lozenges, and apparently not sold in its simple state: compositions of this kind are still met with in India. In the time of d'Orta the drug was an important article of traffic to Malacca and China, as well as to Arabia and Persia.

Notwithstanding these accounts, catechu remained unknown in Europe until the latter half of the 17th century, when it began to be brought from Japan. Schröder in the 4th edition of his Pharmacopaia Medico-Chymica published at Lyons in 1654, briefly describes it as Catechu or Terra Japponica,-" genus terræ exotica," of which he says a little bit had been given to him by the druggist, Matthew Bansa.

In 1671, catechu was noticed as a useful medicine by G. W. Wedel of Jena, who also called attention to the diversity of opinion as to its mineral or vegetable nature. Schröck in 1677 combated the notion of its mineral origin, and gave reasons for considering it a vegetable substance. A few years later, Cleyer who had a personal knowledge of China, pointed out the enormous consumption of catechu for mastication in the East, that it is imported into Japan,-that the best comes from Pegu, but some also from Surat, Malabar, Bengal, and Ceylon.

Catechu was received into the London Pharmacopoeia of 1721, but was even then placed among Terræ medicamentosa."

The wholesale price in London in 1776 was £16 16s. per cwt.; in 1780 £20; in 1793 £14 14s., from which it is easy to infer that the consumption could only have been very small.5

Manufacture-Cutch, commonly called in India Kát or Kut, is an aqueous extract made from the wood of the tree. The process for preparing it varies slightly in different districts.

The tree is reckoned to be of proper age when its trunk is about a foot in diameter. It is then cut down, and the whole of the woody part, with the exception of the smaller branches and the bark, is chopped into chips. Some accounts state that only the darker heart-wood is thus used. The chips are then placed with water in earthen jars, a series of which is arranged over a mud-built fire-place, usually in the open air. Here the water is made to boil, the liquor as it becomes thick and strong being decanted into another vessel, in which the evaporation is continued until the extract is sufficiently inspissated, when it is poured into moulds made of clay, or of leaves pinned together in the shape of cups, or in some districts on to a mat covered with the ashes of cowdung, the drying in each case being completed by exposure to the sun and air. The product is a dark brown extract, which is the usual form in which cutch is known in Europe.

6

In Kumaon in the north of India, a slight modification of the process affords a drug of very different appearance. Instead of evapo

Aromatum Historia, ed. Clusius, 1574. 44. He writes the word Cate.

Usus novus Catechu seu Terræ Japonica, -Ephemerides Nat. Cur., Dec. i. ann. 2 (1671) 209.

3 Ibid. Dec. i. ann. 8 (1677) 88.

Ibid. Dec. ii. ann. 4 (1685). 6.

5 Pegu Cutch is quoted in a London pricecurrent, 21 Aug. 1873, 18s. to 20s. per cwt. 6 Madden in Journ. of Asiat. Soc. of Bengal, xvii. part i. (1848) 565; also private communication accompanied by specimens of tree, wood, and extract from Mr. F. E. G. Matthews, of the Kumaon Iron Works, Nynee Tal.

rating the decoction to the condition of an extract, the inspissation is stopped at a certain point and the liquor allowed to cool, "coagulate," and crystallize over twigs and leaves thrown into the pots for the purpose. How this drug is finished off we do not exactly know, but we are told that by this process there is obtained from each pot about 2 lb. of " Kath" or catechu, of an ashy whitish appearance, which is quite in accordance with the specimens we have received and of which we shall speak further on.

In Burma the manufacture and export of cutch form, next to the sale of timber, the most important item of forest revenue. According to a report by the Commissioner of the Prome Division, the trade returns of 1869-70, show that the quantity of cutch exported from the province during the year was 10,782 tons, valued at £193,602, of which nearly one-half was the produce of manufactories situated in the British territory. Vast quantities of the wood are consumed as fuel, especially for the steamers on the Irrawadi.1

Description-Cutch is imported in mats, bags, or boxes. It is a dark brown, extractiform substance, hard and brittle on the surface of the mass, but soft and tenacious within, at least when newly imported. The large leaf of Dipterocarpus tuberculatus Roxb., the Ein or Engben of the Burmese, is often placed outside the blocks of extract.

Cutch when dry breaks easily, showing a shining but bubbly and slightly granular fracture. When it is soft and is pulled out into a thin film, it is seen to be translucent, granular and of a bright orange-brown. When further moistened and examined under the microscope, it exhibits an abundance of minute acicular crystals, precisely as seen in gambier. We have observed the same in numerous samples of the dry drug when rendered pulpy by the addition of water, or moistened with glycerin and viewed by polarized light.

The pale cutch referred to as manufactured in the north of India, is in the form of irregular fragments of a cake an inch or more thick, which has a laminated structure and appears to have been deposited in a roundbottomed vessel. It is a porous, opaque, earthy-looking substance of a pale pinkish brown, light, and easily broken. Under the microscope it is seen to be a mass of needle-shaped crystals exactly like gambier, with which in all essential points it corresponds. We have received from India the same kind of cutch made into little round cakes like lozenges, with apparently no addition. The taste of cutch is astringent, followed by a sensation of sweetness by no means disagreeable.

Chemical Composition-Extractiform cutch, such as that of Pegu, which is the only sort common in Europe, when immersed in cold water turns whitish, softens and disintegrates, a small proportion of it dissolving and forming a deep brown solution. The insoluble part is Catechin or Catechuic Acid, in minute acicular crystals. If a little of the thick chocolate-like liquid made by macerating cutch in water, is heated to the boiling point, it is rendered quite transparent (mechanical impurities being absent), but becomes turbid on cooling. Ferric chloride forms with this solution a dark green precipitate, immediately changing to purple if common water or a trace of free alkali be used; dilute acids throw down a precipitate.

1 Pearson (G. F.) Report of the Administration of the Forest Department in the

several provinces under the Government of India, 1871-72, Calcutta 1872, part 5. p. 22,

Ether extracts from cutch, catechin. This substance has been shown by Rochleder (1869) to have the formula C13H12O5, and to be a compound of Phloroglucin, C6H6O3, and Escylic Alcohol, C'HO3, less H2O. Catechin dehydrated by drying over oil of vitriol, and then treated with an acid, loses H2O and is converted into brown, amorphous Catechuretin.

An aqueous solution of catechin does not precipitate a solution, either of gelatin, emetic tartar, or of a vegetable alkaloid; but the precipitation at least of the first-mentioned, takes place if the catechin solution is previously boiled for a long time, the result in this case being due to the partial conversion of the catechin into Catechu-tannic Acid. The latter substance is also extracted when cutch or gambier is exhausted with cold water, but from the difficulty of obtaining it free from catechin it has not been thoroughly examined.1

Löwe (1873)2 by exhausting cutch with cold water and then agitating the solution with ether, obtained upon the evaporation of the latter, a yellow crystalline substance which he ascertained to be Quercetin, C27H18012. Its solubility in water is probably favoured by the presence of catechin, water having but very little action upon pure quercetin. The amount of quercetin in cutch is exceedingly small.

When either cutch or gambier is subjected to dry distillation it yields, in common with many other substances, Pyrocatechin, C®H®O2.

Commerce-The importations of cutch into the United Kingdom from British India (excluding the Straits Settlements and Ceylon) were as under, almost the whole being from Bengal and Burma :

1869 2257 tons.

1870 5252 tons.

1871 4335 tons.

1872 5240 tons.

The total value of the cutch imported in 1872, was estimated at £124,458.

Uses-Cutch under the name of Catechu, which name it shares with gambier, is employed in medicine as an astringent.

Analogous Product-Areca-nut Catechu-The seeds of Areca Catechu L., the most elegant palm of India, are called Areca Nuts or Betel Nuts, and yield when boiled in water, an astringent extract which was once supposed to form part of the catechu of commerce; but there is no reason to believe that any of it now finds its way to Europe. Drury states it to be a catechu of very inferior quality, one variety of which, called Cuttacamboo (Katta Kámbu) is chewed with lime and betel-leaf.

3

ROSACEÆ.

AMYGDALÆ DULCES.

Sweet Almonds; F. Amandes douces; G. Süsse Mandeln.

4

5

Botanical Origin-Prunus Amygdalus Baillon var. B dulcis (Amygdalus communis L. var. B dulcis DC.)-The native country of the almond cannot be ascertained with precision. A. de Candolle after 1 Gmelin, Chemistry, xv. (1862) 515. 4 Hist. des Plantes (Monogr. des Rosacées, 1869) i. 415.

2 Fresenius, Zeitschrift für anal. Chemie, xii. (1873) 127.

3 Useful Plants of India, 2nd ed., 1873. 48.

5 Géographie Botanique, ii. (1855) 888.