TRANSACTIONS OF THE SECTIONS. 41 



lyzing gaseous mixtures by ignition with oxygen or liydrogen, in wliich 

 the consequent condensation is appealed to as a basis for an estimate. 

 It appears that the resulting water maj- form gaseous products with any 

 volatile matter which may be present. It is in this way, as I conceive, 

 that olefiant gas, when inflamed as above mentioned with a quantity of 

 oxygen inadequate to saturate it, is expanded into a residual gas larger 

 than that of the mixture before ignition. 



" I remain, gentlemen, with high esteem, your co-labourer, 



" RoBEUT Hare." 



Some Observatio7is on the Foreign Substances in Iron. By Thomas 

 Thomson, M.D. F.R.S., ^-c. Prof, of Chemistry, Glasgow. 



The great difference which exists between different specimens of 

 iron is generally known. The best Swedish iron when compared with 

 British iron, even of the best quality, in point of strength is as 4 to 3. 

 A Swedish wire of a diameter of about y'jth of an inch supports a 

 weight of 450 lbs. without breaking, while the utmost weight that a 

 wire of British iron of the same diameter can bear is 350 lbs. Iron 

 from the mine of Dannemora in Sweden makes excellent steel; Avhile 

 British iron is so ill adapted for the purpose that it is hardly ever con- 

 verted into steel, and never into good steel. Dr. Thomson thought it 

 likely that their differences were owing to something in the British 

 iron which injured its quality and which Mas v.'anting in SM'edish iron. 

 The results of some analyses made by Dr. Thomson do not entirely 

 clear up the question ; but they present some important information 

 on the peculiarities of iron. The following is the statement of the ex- 

 periments. 



" I selected, as best suited to the object which I had in view, the 

 best Dannemora iron, Avliich is all used for conversion into steel, com- 

 mon Welsh iron, which is hardly capable of being converted into steel, 

 and Lowmoor iron from Yorkshire*. Mr. Buthray, a very intelligent 

 steel-maker and iron- smelter in the neighbourhood of Glasgow, was 

 kind enough to supply the specimens, so as to ensure their coming 

 from the places stated. 



" The first remarkable difference in these three specimens is their 

 specific gravity. It was as foUoM's : 



Best Dannemora iron .... 7*9125 



Lowmoor iron 7*3519 



Welsh iron 7*4059 



These differences are much greater than I expected to find : perhaps it 

 will be more intelligible if I state them as follows : 



" If the specific gravity of Dannemora iron be reckoned . 1000 

 the Lowmoor iron will be . 929 

 the Welsh iron .... 939*7 



* Dr. Thomson was informed tLat tliis iron from Lowmoor was smelted with char- 

 coal. 



