Proceedings of the British Association. 103 



from the cabinet of Mr. Hutton, of Newcastle-on-Tyne. It is needless 

 to give the detail of the analyses, which were made with every care : — 

 No. 1. was a specimen of Idocrase from Egg, in Norway ; 2. Idocrase 

 from Slatoush, in Siberia ; 3 Idocrase from Piedmont ; 4. Vesuvian from 

 Monte Somma : 5. Egerane from Eger, in Bohemia. 



12 3 4 5 



Silica 38.75 37.45 3S.25 37.90 38.40 



Alumina 17.35 18.85 17.30 18.10 18.15 



Protox. Iron 8 10 7.75 7.62 4.89 7.40 



Protox. Manganese „ trace 3.50 ,, trace 



Lime 33.60 35.25 32.25 34.69 33.09 



Magnesia 1.50 1.35 .47 3.23 3.02 



99.30 100.35 100.30 98.86 100.06 



The result of these analyses is, that the composition of Idocrase may 

 be represented by the formula, 



7 (FO, MO, CaO MgO) 3 Si0 3 + 5 Al 2 3 Si0 3 which may also be 

 referred back to the fundamental formula of the Garnet, 3 RO, 

 Si0 3 -f- R2 3 Si0 3 . This result however, suggests the idea, that by 

 attending more to the exact representation of the analytical results in 

 the formula, some new light may possibly be thrown on some points 

 in Isomorphism. 



'Experiments on Fermentation,' with some general remarks, by Dr. 

 Ure.* — A dispute having taken place between some distillers in Ireland, 

 and officers of Excise, concerning the formation of alcohol in the vats or 

 tuns by spontaneous fermentation, without the presence of yeasts, the 

 Commissioners of Excise thought fit to cause a sei'ies of experiments to 

 be made upon the subject, and they were placed under my general super- 

 intendence. An experiment was made on the 6th of October, 1837, with 

 the following mixture of corn. 



2 Bushels of Barley weighing 1001b. 5 oz. 



i Bushel of Malt 21 7 



i Bushel of Oats 20 12 



Total, 3 Bushels, weighing 142 8 



The bruised corn was wetted with 26 gallons of water at the tempera- 

 ture of 160° F., and after proper stirring, had 8 gallons more of water 

 added to it at the average temperature of 194 . The mash was again 

 well stirred, and at the end of 45 minutes the whole was covered up, 

 having at that time a temperature of 138° F. Three hours afterwards, 16 

 gallons of wash only were drawn off; being considerably less than should 

 have been obtained, had the apparatus been constructed somewhat dif- 

 ferently, as shall be presently pointed out. The gravity of that wash was 

 1,060; or in the language of the distiller, 60 degrees. After a delay of 



* From the pressure of business before the Section, Dr. Ure did not read this 

 paper, but gave merely a summary of its contents. 



