TRANSACTIOXS OF THE SECTIONS. 43. 



were manganese and silicon ; the f'onnei' to the extent of nearly 2 per 

 cent., and the latter almost to that of fo'^ioth part : the analj'sis gave 



Iron 98-060 



Manganese .... 1-868 



Silicon 0-090 



100.018 

 " In the Welsh iron the quantity of manganese was small, but, owing 

 to an accident, I did not separate it from the iron. The silicon was 

 sensibly the same as in the Lowmoor iron. But in the Welsh iron I 

 found another substance, phosphorus, to the amount of nearly a half 

 per cent. ; this substance is entirely wanting in the Dannemora and 

 Lowmoor irons. The constituents of Welsh iron were 



Iron, with some manganese . 99*498 



Phosphorus 0-417 



Silicon 0085 



100-000 



The presence of phosphorus is probably the reason why Welsh iron is 

 too brittle to be converted into steel. 



" I hardly think that these analyses enable us to account for the 

 striking difference in the specific gravity of these three irons. I rather 

 ascribe this difference to a luechanical cause ; the Dannemora iron has 

 probably been exposed to longer hammering or rolling than either of 

 the British specimens. If this be so, it will in some measure explain 

 its greater strength, for the strength of iron, cceteris paribus, is well 

 known to increase with the degree of hammering to which it has been 

 subjected." 



On (he Sugar in Urine of Diabetes. By Thomas Thomson, M.D. 

 F.R.S., Professor of Chemistry, Glasgoiv, 



" Though the existence of sugar in the urine of persons labouring 

 under the disease called diabetes rnellitus, has been known for more 

 than a century aud a half, having been discovered by Dr. Willis, who 

 died in the year 1678, and though it has been frequei.tly extracted 

 from such urine and exhibited in a state of purity, the author was not 

 aware that experiments requisite to determine its nature had been 

 made. After noticing the statement of Dr. Prout (Phil. Trans. 1827), 

 that such sugar contained gr. 36 to 40 per cent, of carbon, and gr. 60 

 to 64 per cent, water ; Dr. Thomson described the results of some ex- 

 periments which he had recently undertaken to remove the imcertainty 

 which appeared to involve the subject." 



By evaporation, and subsequent digestion in alcohol, the sugar was 

 obtained white, and by i-e-solution in boiling alcohol and slow cooling, 

 acicular crystals were obtained. Specific gravity, when simply dried 

 in air, 1378; heated to fusion (which takes place at 239°) the specific 

 gravity becomes 1*423, while that of common sugar is 1-56, and that 



