June 3, 1898.] 



SCIENCE. 



783 



Tables of numerous test trials on prepared 

 solutions containing from one to 87.5 mg. 

 CrjOs and from one to 47 mg. V^Oj showed 

 errors, with two exceptions, of much less than J 

 mg. and establish the method as trustworthy 

 in competent hands. 



A further table showed the applicability of 

 the method to ores and rocks to which known 

 amounts of CrjO^ and V2O5 had been added. 

 These were fused together with sodium carbon- 

 ate and nitrate ; the silica and alumina were re- 

 moved from the alkaline extract ; phosphorus, 

 chromium and vanadium were thrown down by 

 Hgj(N0a)2 ; the mixed precipitate was ignited ; 

 the residue refused with a little sodium carbon- 

 ate, and in the resulting aqueous extract both 

 chromium and vanadium were estimated, the 

 results being equally as good as those obtained 

 with simple solutions. 



The author suggested that the reaction of H, 

 O2 on CrjOij and V.^Oj in the presence of ether 

 might be utilized to remove the greater part of 

 the chromium prior to titration of the vanadium, 

 since the oxidation product of chromic acid dis- 

 solves in the ether, while that of vanadic acid 

 does not ; also that the brown color produced 

 in vanadic solutions by HjO, might be made the 

 basis of an exact colorimetric method for the 

 estimation of vanadium. 



The next paper was presented by Dr. de 

 Schweinitz and Mr. Marion Dorset and was 

 entitled ' The Mineral Constituents of the 

 Tubercle Bacilli.' The authors, in continuation 

 of their work upon the study of the tubercle 

 bacilli, made a careful analysis of the ash and 

 found a very large percentage of phosphates, 

 calcium, magnesium, potassium and sodium. 

 They pointed out the apparent close connection 

 between the high content of fat and phosphates 

 in the body of the germ and the method of 

 treating tuberculous patients with codliver oil 

 and phosphates. The work is being continued 

 now in the direction of a careful study of the 

 albuminoids of the germ. 



Mr. Fireman presented a paper on ' Some 

 Observations on the Centric Benzene Formula 

 and the Aromatic Character.' The centric 

 formula is ascribed to the unreduced ring, while 

 to the partially reduced ring a structure with 

 the double bonds in the ordinary sense is at- 



tributed. The transformation of the unreduced 

 into the reduced ring and vice versa, as well as 

 the transformation of the ring with the centric 

 structure into the ring with the double bonds 

 and vice versa, must be recognized as a char- 

 acteristic feature of benzene and its derivatives, 

 the aromatic compounds. If this is so, then the 

 centric formula is inapplicable to a ring of 

 either 5, 7 or any odd number of carbon atoms, 

 reduction of such rings being impossible, since 

 the valencies could not be satisfied in case of 

 reduction. Hence the rings of 5 and 7 carbon 

 atoms nearest to benzene in the number of 

 members of the nucleus can not be expected to 

 be endowed with an aromatic character. On 

 the other hand, assuming, as we must, that the 

 tension in the benzene ring, due to the closing 

 of the latter, is small, then a ring of 4 or 8 car- 

 bon atoms would similarly have too much 

 tension, which would be incompatible with 

 such a degree of stability as we find in aromatic 

 compounds. It follows, therefore, that from the 

 standpoint of the centric formula and of ring- 

 tension only the benzene ring can be expected 

 to be a carrier of the aromatic character, 

 which is in entire agreement with the facts. 



The last paper of the evening was presented 

 by Dr. Stokes, and was entitled ' The Meta- 

 phosphimic Acids. ' The paper outlined an at- 

 tempt to explain some of the properties of the 

 meta-phosphimic acids by means of von Baeyer's 

 tension theory. These acids have the general 

 formula (PNO,!!,), and may be regarded as 

 ring compounds. Regarding the rings as poly- 

 gons, the acids actually studied are as follows, 

 the angle between adjacent sides of the poly- 

 gon and its difference from 135°, the angle in- 

 volving the least tension being given : 



Angle be- Difference 

 tween sides, from 135°. 



PaNsOgHe : 120° -15° 



PjNAHa 135° 0° 



P5NA0H10 144° + 9° 



PeNeOijHij 150° +15° 



P,N;0,5Hi6=(P7NA4H„4-H20)... 154.3° -fl9.3° 



Of these acids P^NiOsHj is vastly more stable 

 than the preceding member and represents a 

 maximum stability with a presumable minimum 

 of tension. PsNjOioHio is less stable than 

 P^NiOsHs but more stable than PsNaOeHs, while 



