224 Analyses of Books. 



roads ; one from Linz to Budweis, and the other uniting 

 Prague with Bavaria; a third is projected from Linz to 

 Trieste. Moravia produces 60,000 quints, of soft iron. 



Article XI. 



ANALYSES OF BOOKS. 



On tJie Poisonous Properties of the Hemlock and its Alkaloid 

 Conia. By Robert Christison, M. D., F. R. S., E., &c. — 

 Traiuactions of the Royal Society of Edinburgh, Vol. XIII. 



This paper is devoted to some important investigations with regard 

 to the active principle of conium, particularly as to its chemical and 

 physiological properties. 



The well known hemlock of our woods and hedges, or Conium 

 maculatum of botanists, has been long employed in medicine in the 

 form of extract and tincture ; but strange though it may appear, the 

 nature of the efficient principle in these preparations was only ex- 

 plained a few years ago. In 1827, Giseke succeeded in concentrat- 

 ing the active principle of the plant in a compound with sulphuric 

 acid of such power that two grains killed a small animal in 55 minutes. 

 But it was not till 1831, that Geiger succeeded in separating an 

 oily alkaloid from the extract. He effected this, by distilling with 

 water and caustic potash or lime, neutralizing the liquid with sul- 

 phuric acid, and distilling the liquid over. The residuum consists of 

 sulphate of conein, sulphate of ammonia, and resinoid matter ; the 

 resin and ammonia being produced by the decomposition of part of the 

 conein. In order to obtain the latter, the mass is subjected to the 

 action of a mixture of two parts of rectified spirit and one of sul- 

 phuric ether, which leaves the sulphate of ammonia undissolved. 

 And then the ether and alcohol being distilled carefully off, the 

 remaining sulphate of conein is gently heated with a little water 

 and caustic potash, upon which, there is obtained in the receiver a 

 watery solution of conein in the lower part, and floating on this a 

 layer of nearly pure conein, colourless, transparent, and presenting 

 the appearance of an oil. A little ammonia and water are still 

 present ; the former may be removed by exposing it under the 

 vacuum of an air-pump as long as bubbles of gas continue to escape. 

 This alkaloid exists in greater proportion in the seeds than in any 

 other part of the plant. Geiger ascertained that the dried leaves of 

 hemlock, and some extracts of their j uice do not contain any conein. 

 Dr. Christison has also been able to corroborate these statements. 

 He has found extracts unquestionably well prepared at first, entirely 

 destitute of conein in the course of a short time. A remark, he 

 observes, '* which applies even to the superior extract prepared by 

 Mr. Barry, of London." This is also in consonance with our own 

 experience of the London extracts. The only extract we have found 

 to keep, is that described in Recoj'ds, iv. 72. Of the various 

 extracts examined by Dr. Christison, the largest proportion of conein 



