SCIENCE-GOSSIP. 



SUBSTITUTES FOR PLANT PRODUCTS. 

 By W. E. Ord. 



T N the mysterious processes which constitute the 

 life and growth of plants, there are produced 

 many chemical substances of great value to man- 

 kind. Certain sugars, for example, are elaborated 

 in the growth of fruits, from which they may be 

 obtained by comparatively simple methods. But 

 the dependence upon the cultivation of fruits for 

 our supply of sugar necessitates the expenditure of 

 much time and labour, which might possibly be 

 more profitably devoted to other kinds of industry, 

 and the question arises whether such substances, 

 hitherto only obtained from plant life, cannot be 

 produced by some more direct artificial means. 

 Even though the artificial process may be very 

 difficult and intricate, yet any method which will 

 replace the tedious growth and laborious cultiva- 

 tion of plant life will be deserving of attention. 

 The production of these so - called organic 

 substances was at one time regarded as possible 

 only in the exercise of what was termed " living 

 force," but the many efforts which have been made 

 to prepare or build up such bodies from materials 

 occurring in the inorganic world have now been 

 crowned with startling success. Great progress 

 has been made in this direction in recent years, 

 until now, so far from such artificial formations 

 being impossible, it is considered that when the 

 constitution of an organic substance is thoroughly 

 well known, the means of artificially preparing it 

 may reasonably be expected to be discovered. 



In the case of many organic bodies, however, 

 the difficulty is to obtain an adequate knowledge 

 of their constitution. The chemical compounds 

 found in the mineral kingdom usually contain 

 comparatively simple proportions of the elementary 

 bodies, and their preparation is not, as a rule, 

 difficult ; but the organic compounds are generally 

 not so simple in character and, indeed, the 

 constitution of many familiar substances is so 

 alarmingly complicated as to resist all attempts 

 to analyse them satisfactorily. The chemical 

 changes by which they are naturally produced, 

 and also many of those changes which are con- 

 tinually taking place in the life of plants, are, 

 moreover, very imperfectly understood. In 

 thousands of cases, however, the artificial forma- 

 tion in the laboratory of the simple organic 

 compounds is now quite easy of accomplishment. 

 The chemist can prepare, for example, the well- 

 known tartaric acid, the acid of unripe grapes, and 

 occurring in the crystalline crusts of tartar, 

 deposited in the fermentation of grape juice ; also, 

 citric acid, which gives the sourness to oranges 

 and lemons, and oil of mustard— the cause of the 



pungent properties of mustard paste ; besides 

 many other compounds not so well known in 

 ordinary life. Earnest investigations are being 

 pursued in the endeavour to analyse and prepare 

 the more complex organic bodies met with in 

 nature, with the hope of discovering an easier and 

 cheaper method of production. 



Probably in no field has chemical research been 

 so fruitful as in that of the coal-tar products. 

 From this substance have been prepared valuable 

 compounds, which have entirely replaced many of 

 the natural dyes formerly to be obtained only from 

 plants. The beautiful dye known as alizarin, or 

 madder, is an interesting case of this kind. It is 

 largely used by the calico printer and turkey-red 

 dyer, and produces a red or violet colour accord- 

 ing to the substance with which the fabric is 

 mordanted ; it also forms the insoluble coloured 

 compounds known as " lakes." At one time it was 

 obtained exclusively frcm the rcot of the madder 

 plant, which was extensively cultivated for this 

 purpose in India, Persia, and the Levant, and the 

 trade in the natural product was, until recent 

 years, carried on in France, Italy, and Turkey. 

 The growth of the plant requires a rich soil, and 

 occupies several years. The chemist, however, 

 has discovered a very much cheaper and more 

 expeditious method of obtaining this valuable dye. 

 In 1S68, it was observed that when heated with 

 zinc dust, it yielded the substance anthracene, cne 

 of the coal-tar products, and this observation led 

 to the discovery that alizarin itself could be pre- 

 pared from anthracene. Though the artificial 

 alizarin was for some time difficult to obtain in a 

 state suitable for its industrial application, further 

 attention to the means of preparing it overcame 

 this difficulty, and its manufacture for commercial 

 use, now carried on on a large scale, has entirely 

 replaced the importation of the natural product. 



Many other valuable dyes and important 

 chemical compounds are now obtained from coal- 

 tar, which, at one time an almost valueless bye- 

 product in the manufacture of illuminating gas, has 

 proved a veritable "happy hunting-ground" to 

 the chemist. The valuable blue dye, indigo, 

 suitable for wcollen fabrics, and known as a dye 

 for thousands of years, is still prepared from the 

 indigo plant, which is grown abundantly in Africa, 

 the West Indies, and South America. Indigo has 

 now, however, been prepared from coal-tar. 

 though the process is not yet cheap enough to 

 admit of the artificial indigo being used instead 

 of the natural product in the colour industry. 

 Aniline also, which gives colouring matters of 



