188 NONEXISTENCE OF SUGAR IN DIABETIC BLOOD. 



slate of potash could be taken with safety, its presence 

 would be discerned by means of a solution of iron in as small 

 proportion as almost any known chemiral test. Upon trial 

 of this salt, I found, that a solution of it mi^ht betaken 

 without the least iliconvenience, and that in less than one 

 hour and a half the urine became perceptibly impreonated, 

 and continued so to the fifth or sixth hour, ahiioiigh the 

 quantity taken had not amounted to more than three grains 

 of the salt. 

 Expei'uBer.t. After a few previous trials of the period, when the princi- 

 pal impregnation of the urine might he expected, andwhen 

 the presence of the prussiate (ifit existed in the blood) 

 might with most reason be presumed to orciir, a healthy 

 person, about thiity-four years of age, was induced to take 

 a dose corresponding to three grains aixd a half of the dry 

 salt, and to repeat it every hour to the third time. The 

 urine, being examined every half hour, was found in two 

 hours to be tinged, and to aflbrd a deep blue at the end of 

 four hours. Blood was then taken from the arm, and the 

 coegulum, after it had formed, was allowed to contract, so 

 that the serum might be fully separated. The presence of 

 tl>e prussiate was then endeavoured to be discovered by 

 means of a solution of iron, but without effect : and as I 

 thought, that the redundant alkali (which had been ascer- 

 tained to prevail in this serum) might tend to prevent the 

 appearance of the precipitate, 1 added a small quantity of 

 dilute acid ; but still I could not discern, that any degree 

 of blueness was occasioned by it. 

 The experi- . This experiment, having been repeated a second time 

 »eattepeate4. v?ith the same result, seemed to me nearly conclusive with 

 respect to the existence of some passage, by which substan- 

 ces certainly known to be in the stomach may findtheirway 

 to the bladder without being mixed with the general masg of 

 circulating fluids. 

 No prussiate Being dcbirous of ascertaining, whether the prussiate 

 fownd m ihe cQuld be discovered in any other secretions, I have repeatedly 

 * examined my saliva, at times when the urine has manifested 



c very strong blue, by adding solution of iron, but I could 

 at no time ijerceive the saliva to be tinged. 

 »• aqt ecus 1 have also, during a severe cold, accompanied with pro- 



fuse 



