688 LILIACEvE. 



to combine with chlorine or bromine, and we have failed in obtaining 

 from it any such body as bromaloin. 



Liquid Socotrine aloes, imported into London about 1852, was 

 noticed by Pereira to abound in minute crystals, which he termed the 

 Alo'in of Socotrine Aloes, and regarded as probably identical with that 

 of Barbados aloes. Some fine dry aloes from Zanzibar of very pale hue, 

 in our possession, is in reality a perfectly crystalline mass. 



Histed was the first to assert that the crystalline matter of Socotrine 

 or Zanzibar aloes is a peculiar substance, according neither with bar- 

 baloin nor with nataloin. This observation was fully corroborated by 

 our own experiments,^ made chiefly on the Zanzibar aloes just described, 

 and we shall call the substance thus discovered Socalo'in. In this drug, 

 the crystals are prisms of comparatively large size, such as we have 

 never observed in Natal aloes. The}' cannot be so easily isolated as 

 nataloin, since they are nearly as soluble as the amorphous matter sui*- 

 rounding them. Histed recommends treating the powdered crude drug 

 with a little alcohol, sp. gr. O'OGO, and strongly pressing the pasty mass 

 between several thicknesses of calico; then dissolving the yellow 

 cr}' stalline cake in warm weak alcohol, and collecting the crystals which 

 are formed by cooling and repose. 



Socaloin forms tufted acicular prisms, which by solution in methylie 

 alcohol may be got 2 to 3 millimetres long. It is much more soluble 

 than nataloin. At ordinary temperatures, 30 parts of alcohol, 9 of acetic 

 ether, 380 of ether, 90 of water are capable of dissolving respectively 

 one part of socaloin ; while in methylie alcohol, it is most abundantly 

 soluble. Socaloin is a hydrate, losing when dried over oil of vitriol 11 

 to 12 per cent, of water, but slowly regaining it if afterwards exposed to 

 the air. Its elementary composition according to the analysis made by 

 one of us (F.) is O"^'*Il^*0^^ + 5 H-0. We have not succeded in obtaining 

 any well-defined bromine compound of socaloin. 



The three aloins, Barbaloin, Xatalo'in, and Socaloin, are easily dis- 

 tinguished by the following beautiful reaction first noticed by Histed : 

 — a drop of nitric acid on a porcelain slab gives with a few particles of 

 barbaloin or nataloin, a vivid crimson, ^ but produces little effect with 

 socaloin. To distinguish barbaloin from nataloin, test each by adding a 

 minute quantity to a drop or two of oil of vitriol, then allowing the 

 vapour from a rod touched with nitric acid to pass over the surface. 

 Barbaloin (and socaloin) will undergo no change, but nataloin will 

 assume a fine blue.^ 



The researches of E. von Sommaruga and Egger in Vienna (1874) 

 have been directed in particular to the aloin of Socotrine aloes. The 

 melting point of this aloin was found to be between 118° and 120° C, 

 that of barbaloin being much higher. The authors conclude that the 

 three form an homologous series, that their composition may probably 

 be represented thus : — 



Barbaloin C^'H^oQ" 



Nataloin CisHi^'O" 



Socaloin C^sHieo^ 



^ Fllickiger, Crystalline Principles in but permanent with nataloin unles.s heat 



A loet, — Pharm. Joiirn. September 2, 1 87 1 . be applied. 



195. -^ These reactions may be sometimes got 



■^ Rapidly fading in the case of barbaloin, even with the crude drugs. 



