February 23, 1922] 



NATURE 



245 



Obituary. 



Prof. Giacomo Ciamician. 



I 



BV the death of Prof. Giacomo Luigi Ciamician, 

 of the University of Bologna, Senator of the 

 Kingdom of Italy, which occurred on January 2 of 

 the present year, Italy has lost one of her most dis- 

 tinguished men ol science, and modern chemistry 

 one of the most assiduous and most successful of its 

 cultivators. 



Ciamician's work was characterised by the 

 breadth and originality of its grasp. It ranged 

 practically over every department of the science — 

 spectrum analysis, electrolytic dissociation, organic 

 synthesis by plants, chemical action of light, spatial 

 chemistry — but it was mainly concerned with prob- 

 lems of organic chemistry, and it is by his labours 

 in certain special fields of this branch that he will 

 be chiefly remembered. One of his earliest investi- 

 gations was an inquiry into the chemical nature and 

 constitution of the resins and gum-resins — a con- 

 fessedly difficult and complicated subject forty-five 

 years ago when he first attacked it. By distilling 

 abietic acid, the main constituent of colophony or 

 ordinary rosin, with zinc-dust in a current of hydro- 

 gen — a reduction -process which had been already 

 proved to be of general utility — ^he obtained a 

 number of aromatic derivatives, notably toluene, 

 »/-ethylmethylbenzene. naphthalene, methylnaphtha- 

 lene, and methylanthracene. Gum-benzoin simi- 

 larly treated yielded similar products, together with 

 small quantities of xylene. Elemi-resin also 

 yielded toluene, and ethylmethylbenzene and ethyl- 

 naphthalene, but no naphthalene or methylanthra- 

 cene. Gum-ammoniacum gave both para- and meta- 

 xylenes and meta-ethylmethylbenzene, and the 

 methylether of ortho-ethylphenol, but no naphtha- 

 lene derivatives. These observations are of con- 

 siderable interest, but they do not necessarily throw 

 light upon the constitution of the terpene-resins, as 

 certain of the products may be the result of second- 

 ary reactions. In fact, aldehyde-resin, obtained 

 from ordinary aldehyde and therefore not an aro- 

 matic derivative, on reduction with zinc-dust, was 

 found to yield ethylbenzene, meta- and para-ethyl 

 toluene, and methylnaphthalene. 



In 1 88 1 Ciamician attacked the chemistry of 

 pyrrole, a constituent of the fetid-smelling product 

 obtained by heating bones in the preparation of 

 animal charcoal, and hence termed bone-oil or 

 Dippel's oil, from the name of the chemist who, so 

 far back as 17 ii, first attempted to get an insight 

 into its nature. This product has been known for at 

 least four centuries, and has been the subject of 

 re|)eated inquiry. 



The investigation of pyrrole, first isolated by 

 Runge in 1834, its congeners and derivatives, occu- 

 pied Ciamician, at intervals, for upwards of a 

 quarter of a century, and he published, partly 

 alone, and partly in conjunction with Dennstedt, 

 Weidel, Anderlini, Magnaghi, Magnanini, Silber, 

 and Zanetti, no fewer than sixty communications on 

 its chemistry. In 1904 he reviewed all this work 

 in a lecture delivered to the German Chemical 

 NO. 2730, VOL. 109] 



Society, afterwards printed in vol. 37 of its 

 Berichte. It forms a remarkable chapter in the 

 development of a section of organic chemistry with 

 which Ciamician 's name will always be associated 

 He established the nature of pyrrole as a secondary 

 amine, its carbon and hydrogen atoms forming a 

 closed chain, the hydrogen atoms being symmetri- 

 cally situated with respect to the carbon atoms, as 

 suggested by Baeyer. Its formation from succini- 

 mide by distillation with zinc-dust, and the fact 

 that it yields succinaldehyde dioxime by the action 

 of hydroxylamine, conclusively established this view 

 of its constitution. 



Ciamician 's work on pyrrole had many side 

 issues. He elucidated its relations, not only to the 

 substances with which it is associated in bone-oil, 

 such as pyridine, into which he showed it might be 

 converted, but also to indole and indigo. He 

 was naturally led to the study of the products of the 

 destructive distillation of gelatin, and, with Weidel, 

 discovered pyrocoll, which he regarded as a quinone 

 of the constitution 



QH,N<; >C4H3N, 



or as the anhydride of carbopyrrolic acid, of which, 

 with Silber, he prepared a number of derivatives, 

 and eventually eff^ected its synthesis by heating a 

 solution of carbopyrrolic acid in acetic anhydride, 

 when pyrocoll, with all the properties of that 

 obtained from gelatin, sublimes. 



Pyrrole derivatives are concerned in vital pro- 

 cesses. They have been found in plants, and 

 certain of them have been shown by Willstatter to 

 exist among the decomposition products of chloro- 

 phyll and of haemoglobin — one more illustration of 

 the remarkable analogies which exist between these 

 substances so important in their physiological 

 functions. 



Ciamician was early attracted to plant chemistry, 

 and made important contributions to our knowledge 

 of the nature and constitution of substances pro- 

 duced by photosynthetic processes in the vegetable 

 organism. He determined the constitution of 

 apiole, a substance found by von Gerichten in 

 parsley seeds, and of the analogous compounds 

 safrole, the chief constituent of the essential oil of 

 sassafras and found in other natural oils, leaves, and 

 fruits, and eugenol, a still more widely dis- 

 tributed natural product. With Silber he investi- 

 gated the constituents of coto- and paracoto-bark, 

 substances of pharmacological interest, and derived 

 from plants growing in Bolivia and Venezuela. 



A growing plant is a living laboratory in which 

 synthetic processes may be directed, controlled, or 

 modified, as in the human organism, by external 

 means. In conjunction with Ravenna, Ciamician 

 studied the eff'ect of the introduction of various 

 natural organic products into plants, with the view of 

 determining their fate, or their influence on the life- 

 history or development of the plant. They showed 

 that plants will tolerate and utilise glucosides, such 



