304? Royal Society, 



is in containing, after digestion, a large quantity of fat in a very fine 

 state of division. The supposition that the disease consists in an 

 accumulation of fat in the blood, which is thrown out by the kidneys, 

 carrying with it albumen, fibrine, blood-globules and salts, is altogether 

 disproved, both by actual analyses of the blood, and by the frequent 

 occurrence of a jelly-like coagulum in the urine when no white fatty 

 matter can be seen to be present. 



3. The disease consists in some change in the kidney by which 

 fibrine, albumen, blood-globules and salts are allowed to pass out, 

 whenever the circulation through the kidney is increased; and if at 

 the same time fat is present in the blood, it escapes also into the 

 urine. That this change of structure is not visible to the naked eye 

 on post-mortem examination, Dr. Prout long since demonstrated ; 

 and in a case of this disease which was in St. George's Hospital, and 

 was examined at Plymouth, no disease of the kidney was observed. 

 From the total absence of fibrinous casts of the tubes from the urine, 

 it is not improbable that by the microscope a difference may be de- 

 tected in the structure of the mammary processes, rather than in 

 that of the cortical part of the kidneys. 



April 25. — "On the Temperature of Steam and its corresponding 

 Pressure." By John Curr, Esq. Communicated by J. Scott Russell, 

 Esq., F.R.S. 



The author states that it is intended in this paper to propose a 

 simple law to determine the pressure of steam corresponding to any 

 given temperature, irrespectively of experiment, taking as the sole 

 datum, that the vaporizing point of water under a given pressure is 

 100 degrees, that number being taken to correspond with the scale 

 of Celsius ; also to construct formulae in accordance therewith ; and 

 afterwards to compare their results with the actual experiments of the 

 Academy of Sciences of Paris. He further states that the rationale 

 of the subsequent formulae is expressed as follows. Let it be con- 

 ceived that & given quantity of water is vaporized under the condition 

 that the pressure thereon is increased in the same ratio that the vo- 

 lume is increased, or that at intervals of temperature 1, 2, 3, &c. the 

 volume is increased the same or in equal proportions; the tempe- 

 rature of the volume will be increased exactly as the square of the 

 temperature indicated by the thermometer, supposing the instrument 

 to be a true measure of temperature, and as the square of the vo- 

 lume ; and the same of the pressure. 



Steam being generated from an i?idefinite quantity of water and 

 confined within a limited space, as in the usual boiler, he considers 

 the foregoing case is reversed; for the volume being constant, the 

 action of the fire is entirely exerted in producing increased elastic 

 tension of the vapour ; therefore the temperature of the steam at the 

 interval 1 to 2 degrees is increased inversely in the duplicate ratio 

 of the ratio in the case first described; that is, the pressure is in- 

 creased directly as the square of the square, or fourth power of the 

 temperature ; whence the following law. The pressure of steam 

 generated in the usual steam-boiler is directly proportional to the 

 fourth power of its temperature, when measured by a true scale. 



