476 THIRD REPORT 183S. 



4. That Mr. Johnston ' be requested to undertake the expe- 

 rmients which have been suggested to the Committee, into the 

 comparative analysis of Iron in the different stages of its ma- 

 nufacture. 



*5. That a series of experiments on the effects of long-con- 

 tinued heat be instituted at some iron-furnace, or in any other 

 suitable situation; and that a sum not exceeding 50/. be placed 

 at the disposal of a Sub-Committee, consisting of Professor 

 Daubeny, Rev. W. V. Harcourt, Professor Sedgwick, and 

 Professor Turner, to meet any expense which may be in- 

 curred ^. 



*6. That inquiry be made as to the most perfect method of 

 purifying Mercury, and that the true specific gravity of the 

 metal be determined. 



*7. That an examination be made into the nature and quan- 

 tity of the gases given off from thermal waters, whether there 

 be any variation in these respects according to season of the 

 year, hours of the day, or condition of the atmosphere ; and 

 whether there be any changes of temperature in the same 

 waters. 



*8. That the gaseous products which are discharged from 

 the chimneys of smelting and other furnaces and fireplaces be 

 examined, at various periods of the operations cari'ied on in 

 them, with a view of ascertaining the compounds which are 

 formed when the processes are most successfully conducted, 

 and also of detecting the existence of compounds which may 

 perhaps be new or valuable. 



MINERALOGY. 



1. That Professor Miller be requested to undertake an ex- 

 amination of the form and optical characters of those Crystal- 

 lized Bodies which have not been previously determined, and 

 that Chemists be i?ivited to send him specimens of perfect ar- 

 tificial Crystals. 



2. That Dr. Turner, Professor Miller, Mr. Brooke, and the 

 Rev. Wm. Whewell, be requested to cooperate in prosecuting 

 and promoting the following inquiries, with a view to examine 

 the theory of Isomorphism, and the connexion between the 

 crystalline forms and chemical constitution of Minerals : 



' Mr. Johnston reported the progress of his researches to the Cambridge 

 Meeting. 



' These experiments have been instituted by Mr. Harcourt, in Yorkshire, at 

 the Low Moor Iron Works, the property of Messrs, Hird and Co., and at the 

 Elsecar Furnace, belonging (o Earl Fitzwilliam. 



