253 



Heat nearly to Itoiliiig. stirring' occasionally and adding more bromine 

 water, if necessary, till the precipitate of manganese dioxide separates. 

 Filter and wasb. The precipitate adhering to the beaker need not be 

 removed, bnt the beaker must be rinsed thoroughly. Place the beaker 

 under the funnel containing the precipitate and drop upon the latter, 

 from a burette, the solution of ferrous ammonium sulphate till solution is 

 complete, breaking up the precipitate occasionally with a fine stream of 

 water from a wash bottle. Unless the manganese exceeds 0.4 per cent., 

 not more than 20 cc. of the solution need be used. Wash out the filter 

 and titrate the filtrate with the standard permanganate solution. The dif- 

 ference between the number of cc. of permanganate used and the amount 

 which would have been employed if no manganese dioxide had been dis- 

 solved in the ferrous ammonium sulphate, multiplied by the manganese 

 equivalent of the solution, will give the amount of manganese in one 

 gram of iron. 



The method was tested with sohitions containing kno-um amounts of 

 manganese and gave accurate results. The method avoids the evapora- 

 tion to dryness required by Yolhard's method and also gives a very sharp 

 end reaction, while the end reaction of Yolhard's method is very difli- 

 cult to see. 



The paper is published in the .Jour. Amer. Chem. Soc, 2\. 243. 



A New Hydroxy-dihydro-alpha-Campiiolytic Acid. 

 W. A. NoYES AND A. M. Patterson. 

 Dihydro-alpha-campholytic acid was prepared by W. M. Blanchard and one 

 of us last year. From this the aipha-brom. derivative, C,Hi4 Zgr ^^^ ^^^^ '^^^' 

 responding hydroxy acid, CsHh Zq'h '^' ^^^^ been prepared. When the latter is 

 warmed with lead peroxide and dilute sulphuric acid a ketone is formed which 

 should be identical with the 2-3.3 trimethyl cyclopentanone, prepared synthet- 

 ically by one of us, if the Perkin-Bouveault formula for camphor is correct. 

 From the melting point of the oximes the two ketones appear to be different, and 

 the formula for camphor referred to seems to be no longer tenable. The rejection 

 of that formula, however, compels us to suppose a transfer of a methyl group from 

 one carbon atom to another in reactions which take place readily at ordinary 

 temperatures under the influence of sulphuric or hydrobromic acid. 



