On the Action of tlte Blood. 123 



discussions, which have, however, left the matter undecided. Some 

 experiments, to be afterwards detailed, lead MM. Prevost and 

 Dumas'to think; I", That the urea is eliminated by the kidneys in 

 proportion as it is formed ; 2. That when this organ is extracted, 

 the blood retains the whole of the urea. Now if it be admitted, 

 that the same thing happens with the saccharine matter, it may 

 without difficulty be conceived that in the cases where the kidney 

 does its duty, the whole sugar disappears from the blood, and that 

 in those where it performs its functions in a partial manner, sensi- 

 ble quantities of sugar will still be found in that liquid. It cannot 

 be expected to be found in any very notable mass, as long as the 

 action of the kidney has not been entirely destroyed. These se- 

 veral considerations seem to them to establish that it is with the 

 sugar of diabetic persons as with the urea, and they have some 

 reasons for thinking that this principle exerts a diuretic action, 

 from which the chief symptoms of diabetes may be deduced. We 

 may also find here illustrations of some phenomena of the gout, 

 which confirm the discovery itself. The presence of concretions of 

 lithate of soda in the joints might have led us to think that this 

 principle existed in the blood. We know besides, that the urinary 

 secretion is loaded with a large portion of lithic acid, when the 

 paroxysm affects the kidneys, and that the articulations briskly 

 attacked, are the only ones which contain the concretions of the 

 alkaline lithate. If analysis proved, that at the beginning of the 

 attack the blood contains more lithic acid than the kidney can 

 possibly draw off, we would recognise in the general disturbance 

 which forms the commencement of the paroxysm, the result of this 

 morbid action of the blood, and in the point affected, a mo- 

 mentary seat of the secretion. The characters of the urine will 

 henceforth acquire o very great interest, as they may serve to in- 

 dicate the state of the mass of the blood, and the kind of alter- 

 ation which this important fluid has undergone. 



Physiologists, curious of ascertaining for themselves the truth of 

 the facts announced in this Memoir, will not experience much dif- 

 ficulty. Five ounces of blood from a dog which had lived without 

 kidneys for only two days, afforded more than twenty grains of urea; 

 and two ounces of the blood of a cat, in the same circumstances, 

 yielded more than ten grains of it. These quantities are perfectly 

 appreciable by the least experienced chemists. The above analy- 

 ses have been successfully repeated by M. Vauquelin ; and his 

 pupil M. Segalas has shewn that urea is a very powerful diuretic. 



14. On the Electro-Magnetic Multiplier of Schwcigger, and on some 

 of its applications. By M. Oersted. 



Immediately after the discovery of electro-magnetism, M. Schweig- 

 ger, Professor at Halle, invented an apparatus well adapted 



