48 



REPORT 1870. 



Para-series. 



Meta-serics. 



acid, Ci2 He O12, or benzol in which the 6 atoms of hydrogen are replaced by the 

 monad radical carboxyl (CO OH), as benzoic is monocarbonic acid, or benzol 

 in which one of hydrogen is replaced by carboxyl. The most interesting portion of 

 Baeyer's research, however, lies in the intermediate acids, partly new and partly 

 acids already prepared, which he has shown lie between mellitic and benzoic, and in 

 which from one to six atoms of hydrogen in benzol are respectively replaced by 

 carboxyl. Nor is this all ; for he has proved that, with two exceptions, each of 

 these six acids is capable of existing in three isomeric modifications, thus affording 

 us an insight into the arrangement of the molecule of these aromatic compounds ; 

 for the simplest mode of explaining these numerous isomers is that given by 

 Baeyer, in the different order in which the several atoms of hydrogen in the benzol 

 molecule are replaced. Thus in the first or ortho-series, the hydrogen atoms in 

 benzol being numbered in regular succession, they are replaced in the same regular 

 succession. In the second or meta series the order is 1, 2, 3, 5, &c., whilst the third 

 or para-series take open order, as 1, 2, 4, 5, &c. 

 Thus we have : — 



Ortho-series. 

 Mellitic or benzol 



hexacarbonic. 

 Unknown. 

 P3Tomellitic or ben- 

 zol tetracarbonic. 

 Trimesinic or benzol Hemimellitic. Trimellitic. 



tricarbonic. 

 Phthalic or benzol Isophthalic. Tetraphthalic. 



dicarbonic. 

 Benzoic or benzol 

 monocarbonic. 

 Amongst the most interesting series of new organic bodies are those in which 

 tetrad silicon partly replaces carbon. Our knowledge of these substances is 

 gradually becoming more complete ; the last new member prepared by Friedel and 



Ladenburg, is silico-propionic acid, ^-A t| , the first of a series of cai-bo-silicic acids 



containing the radical SiOoH. 



The interesting researches of Matthiessen and Wright on morphine and codeine 

 have thrown a new light on the constitution of these opium alkaloids. Treated 

 with hydrochloric acid, morphine loses one molecule of water, and gives rise to a 

 new base, apomorphine, 



Isopyromellitic. Unknown. 



C„ H,, NO3 

 Morphine. 



H, -1- C„ n„ NO,, 

 Apomorphine. 



which differs in a remarkable manner from morphine, both in its chemical and 

 physiological actions, being soluble in alcohol, ether, and chloroform, whereas 

 morphine is nearly insoluble, and acting as the most powerful emetic known, ^l' 

 of a grain producing vomiting in less than ten minutes. Codeine, which only 

 differs from morphine by CH^, also yields apomoi-phine on treatment with hydi'o- 

 chloric acid, methylchloride being at the same time eliminated. 



An important application of the dehydrating and carbon-condensing power of 

 zinc chloride, long known in its action on alcohol to produce ether, has been made 

 by Kekul^ in the reduplication of aldehyde to form croton aldehyde with loss 

 of water, 2 (C^HjO) — HoO = C^HgO. This croton aldehyde is also probably 

 formed as an intermediate product in the manufacture of chloral from aldehyde, 

 and gives rise to the formation of croton chloral, C^ H3 CI3 0. 



The discovery of the sedative properties of chloral-hydrate by Leibreich marks 

 an era in medical chemistry second only to the discovery of the anaesthetic properties 

 of chloroform. Chloral not only combines with water to form a solid hydrate, but 

 also forms solid alcoholates; but these bodies appear to possess quite different 

 medicinal properties from the hydrate, and it is important that no alcoholate 

 shoidd be present. 



The chemistry of colouring-matter has lately received an enormous impetus in 



