158 J.C. Marquart's Report of the Progress of Photochemistry 



amined it more recently with Fr. Nees von Esenbeck* and 

 found as its contents a peculiar wax which melts at 48° Reaum., 

 and also a series of peculiar resins. The substance called the 

 insoluble lac-resin (lac of John) must be considered as repre- 

 senting the caoutchouc in this milk-sap, which resists the 

 common solvents, and is only affected by acidulated alcohol. 

 Nearly related to this is the Beta-resin of the lac, which 

 part the authors consider as insoluble in aether and weak al- 

 cohol, and only soluble in absolute alcohol, or that of 90°. By 

 certain manipulations it passes over into the lac of John, and 

 it may well be supposed that it owes its solubility in alcohol to 

 the so-called lac acid which is mixed with it, the nature of 

 which the authors were not able to ascertain on account of 

 its rare occurrence. That part of the seed-lac which is so- 

 luble in spirits of wine and aether the authors named the 

 Alpha-resin of the lac, and found the same to be again com- 

 posed of the first alpha-resin, which is hard, friable, of a gold 

 colour, and which gives with alkalies and oxides of lead beau- 

 tiful purple red combinations, while the second alpha-resin is 

 a yellow soft resin, and has in a very great degree the peculiar 

 smell of shell-lac. 



Scarcely any section of the vegetable formative parts is in 

 greater want of a revision than that of the resins, whose dif- 

 fusion is so general, and whose varieties almost keep pace with 

 or appear even to surpass, the number of species of plants. 

 We are convinced that a rational examination of this part of 

 phytochemistry would give quite different results. In no ana- 

 lysis does there ever fail to be a resin among the educts enu- 

 merated ; even in Sphterococcus crispus M. Herberger found 

 two different ones, which however, as in many other analyses, 

 are so dubiously characterized, that we may here pass them 

 over in silence without keeping anything important from our 

 readers. Not even is a consistent division followed in the 

 description of these bodies; and it is probable that various 

 mixed and changed substances are frequently cited as peculiar 

 resins. We will therefore in this place only mention a few cry- 

 stallizing resins, like that which Mr. Landererf separated from 

 the liesina Guajaci tiativa, which crystallizes in fine needles, 

 void of smell, soluble in aether and boiling alcohol, and be- 

 came by concentrated nitric acid of a lively grass green colour, 

 and whose spirituous solution had acid reaction. A similar resin 

 was found by Geiger in the bark of the root of Cormisforida, 

 the solution of which, however, possessed neither an acid nor 

 an alkaline reaction. In general, those resins which are not very 



• Geiger and Liebip's Ann. dcr Pharm., vol. xiii. part 3. 

 f Buehn. Rcpcrt., Hi. p. 1)3. 



