Mr. Venables on Siliceous Gravel. 237 



Chelmsford, I again submitted it, under a less objectionable 

 form, to the action of the re-agents already mentioned and with 

 similar results. I then mixed it with soda, and exposed it to 

 the flame of the blowpipe, when it melted slowly, and at last 

 fused into a semi-vitreous globule, with scarcely any degree of 

 transparency. These refractory characters place the nature of 

 this substance beyond any doubt. Being in the habit for the 

 last fourteen or fifteen years of examining the general proper- 

 ties of the urine in all cases, where practicable, in which I am 

 concerned, and having never met with any similar production, 

 I felt doubtful as to the urinary origin of this substance. I 

 have not the slightest suspicion of any attempt at imposition * 

 on the part of this poor woman ; but the siliceous substance 

 might have been in the utensil, and the patient seeing it, after 

 having voided the urine, might have imagined that it passed 

 from the bladder with this fluid. This makes the loss of the 

 other little calculus, which was passed at a day or two's interval, 

 the more to be regretted, as its nature would have tended, in 

 some degree, to clear up the mystery. I was not, therefore, 

 inclined to attach much importance to this single instance, 

 more especially as its urinary origin was not unequivocally 

 proved. But having lately met with another instance in which 

 siliceous matter, in the form of very minute angular grains, 

 has been passed with the urine, I can no longer doubt the 

 circumstance, and have therefore determined to present the 

 facts to the scientific part of the profession. 



The patient, in this instance, is also a married woman, 

 thirty-four years of age, of very delicate constitution, and, in 

 general, bad health. She has also, for a long timef, suffered 

 with symptoms of urinary derangement, and has frequently 

 passed blood with the urine. There is also a considerable 

 degree of uterine disease, as, although she has been several 

 times pregnant, she has never given birth to a living child, 

 nor gone her full time ; yet her mother has had fifteen 



* Dr. Marcet states, that patients frequently attempt to impose upon 

 medical men, without any ostensible motive. Could he have met with 

 instances of the above description, and considered them as attempts to 

 deceive and impose upon the practitioner? 



t She states since 1819. 



R 2 



