ON THE TRESENT POSITION OF THE CHEMISTRY OF THE GUMS. 229 



and the mucilages or gum solutions obtained from linseed and from 

 quince seed. 



At that period the activity awakened by the new ideas in chemistry 

 was the cause of various attempts to ascertain the nature of the substances 

 that form the different gums. The work then done resulted in the 

 descriptions of the properties of a few gum substances, believed to be 

 individual chemical compounds, to which the names bassorin, cerasin, and 

 arabin were given. After these names had been assigned, chemists, 

 dominated by the idea that the number of organic compounds was only 

 small, on investigating a gum identified its constituents with one or more 

 of these substances. As these identifications rest on only a few simple 

 properties, but little weight attaches to them. In fact, it now appears that 

 the number of gum compounds is very considerable ; consequently, in 

 reading the literature of the last century, statements that the author had 

 found the presence of arabin, or cerasin, or bassorin, &c., do not throw 

 any certain light on the nature of the substance found, as it cannot be 

 safely inferred that it is the same substance as the arabin, or cerasin, or 

 bassoi'in, &c., found in another natural product by another author. 



It may be of some interest to trace the origin of these names, so often 

 attached in the last century to the components of the different gums. 



Bassorin. — In 1811 Vauquelin published an examination of gum 

 Bassora, and in the same year Pelletier, who was engaged in examining 

 several gum resins, published a paper in which he proposed the name 

 bassorine for the substance constituting the gum Bassora described by 

 Vauquelin, since he believed he had found the same substance in the gum 

 resins. Gum Bassora appears to be a gum having properties somewhat 

 similar to those of tragacanth, but not to be so highly valued. It derives 

 its name from the Turkish port now called Basra, at the head of the Persian 

 Gulf, from which there is a considerable export of gums. A ' gum Bussora ' 

 is still quoted in the London market reports, but whether it is the same 

 gum as that examined by Vauquelin, or whether it really comes from 

 Basra, is not easy to say, since trade terras of the kind are often mis- 

 leading. 



Cerasin. — In 1812 John, who was aware of Vauquelin's work, 

 published an examination of several gums derived from the genus Prunns, 

 and gave the name of cerasin or prunin to the gum substance he obtained 

 from the fruit of the plum known as Mirabel, and also from the stem of 

 the wild cherry-tree, Prutbus avium. He found that the gum of the 

 sweet cherry-tree was of a different nature. The term ' prunin ' did not 

 come into use, but ' cerasin ' has often been used. 



Arabin and Para Arabin. — In 1833, Chevreul, in reporting on a 

 memoir on the gums, written by Guerin, gave the name arabine to the 

 gum substance of gum arable and of gum Senegal, and remarked that if 

 cerasin should prove to be identical in composition with arabin it ought 

 to be called para arabine. 



Roughly speaking, it may be said that in the descriptions of the gums 

 the part soluble in cold water was put down as arabin, and the part in- 

 soluble in cold water was put down as cerasin or bassorin. 



Metagummic Acid and Gummic Acid. — In 18G0, Fremy published a 

 paper in which he described a substance obtained by pouring a strong 

 solution of gum arable on to concentrated sulphuric acid. This substance 

 is insoluble even in boiling water, but alkalies cause it to dissolve, and 

 then acids do not reprecipitate it from the solution. He gave the name 



