Chemical Composition—Kamala has been analysed by Anderson of Glasgow (1855) and by Leube (1860). From the labours of these chemists, it appears that the powder yields to alcohol or ether nearly 80 per cent. of resin. We find it to be soluble also in glacial acetic acid or in bisulphide of carbon, not in petroleum ether. By treatment of the resin extracted by ether with cold alcohol, Leube resolved it into two brittle reddish yellow resins, of which the one is more easily soluble and fuses at 80° C., and the other dissolves less readily and fuses at 191°. Both dissolve in alkaline solutions, and can be precipitated by acids without apparent change.
Anderson found that a concentrated ethereal solution of kamala allowed to stand for a few days, solidified into a mass of granular crystals, which by repeated solution and crystallization in ether were obtained in a state of purity. This substance, named by Anderson Rottlerin,[2139] forms minute, platy, yellow crystals of a fine satiny lustre, readily soluble in ether, sparingly in cold alcohol, more so in hot, and insoluble in water. The mean of four analyses gave the composition of rottlerin as C₂₂H₂₀O₆.
We have been able to confirm the foregoing observations so far as that we have obtained an abundance of minute acicular crystals, by allowing an ethereal solution of kamala to evaporate spontaneously to a syrupy state. But the purification of these crystals, which was also attempted by our friend Mr. T. B. Groves,[2140] was unsuccessful, for when freed from the protecting mother-liquor, they underwent a change and assumed an amorphous form. We have, on the other hand, succeeded in isolating the crystals from the “Kamalin,” as sold by E. Merck of Darmstadt. By fusing them with caustic potash we obtained paraoxy-benzoic acid ([see page 408]).
Uses—The drug is administered for the expulsion of tapeworm; it has also been used as an external application in herpes circinnatus. In India it is employed for dyeing silk a rich orange-brown.
Adulteration—Kamala is very liable to adulteration with earthy substances, even to the extent of 60 per cent. This contamination may easily be known by the grittiness of the drug, and by a portion of it sinking when it is stirred up with water, but in the most decisive manner by incineration. Sometimes kamala contains an undue proportion of foreign vegetable matter, as remains of the capsules, leaves, etc., which can partly be separated by a lawn sieve. We have met with a large quantity of very impure Kamala in the London market (1878), which was offered for cleaning polished metallic surfaces.
Substitute—A very remarkable form of so-called kamala was imported in 1867 from Aden by Messrs. Allen and Hanburys, druggists, of London.[2141] It arrived neatly packed in oblong, white calico bags, of three sizes, each inscribed with Arabic characters, indicating with the name of the vendor or collector, a native of Hurrur, the net weight, which was either 100, 50, or 25 Turkish ounces. No more than two supplies, in all 136 lb., could be obtained.
The drug was in coarser particles than kamala, of a deep purple, and had a distinct odour resembling that which is produced when a tincture of kamala is poured into water. It had been carefully collected and was free from earthy admixture, yet it left upon incineration 12 per cent. of ash. Under the microscope it presented still greater differences, the grains being cylindrical or subconical, 170 to 200 mkm. long, by 70 to 100 mkm. broad, with oblong resin-cells, arranged perpendicularly in three or four storeys; mixed with the grains were a few long, simple hairs. Another fact of some interest is, that at a temperature of 93° to 100° C., this drug becomes quite black, while kamala undergoes no change of colour.
In 1878 our friend Professor Schär was informed by a Swiss firm, Messrs. Furrer and Escher of Aden, that Kanbil, Qinbil or Kamala are unknown there. But they sent under the name of Vars a powder, which Prof. Schär as well as one of us (F.) find identical with the drug which had been imported by Messrs. Allen and Hanbury. Prof. Schär was also informed that Vars is used chiefly in the coast districts of Mascat (Oman) and Hadramaut, in skin diseases, for expelling the tape worm and as a dye.
Thus the appellation Wurrus or Waras is to be restricted to the dark purple or violet glands occurring in eastern Africa and Yemen, although the Waras sent to one of us[2142] by Vaughan was kamala.
As to the mother plant of Waras[2143] we have no information to offer; we attempted in vain to ascertain its origin. It is evident that it is the “black Abyssinian” powder already alluded to at page 573.