196 PROCEEDINGS OF THE AMERICAN ACADEMY 



Dr. Hayes called the attention of the Fellows to the fact, 

 that 



" The urinary deposition called red sand, which presents such well- 

 defined crystals, is a compound body, having generally a large quan- 

 tity of oxalate of lime crystallized with it. Crystals of various forms 

 and colors were shown under the microscope. Lithic acid, ammonia, 

 coloring matter, and oxalate of lime are the most common and obvi- 

 ous ingredients assuming a crystalline form. Oxalate of lime, as 

 inferred from more than twenty-five analyses of different urine samples, 

 is always present, and may be detected both by spreading a layer of 

 aqua ammonia on the surface of recent urine, when the salt crystal- 

 lizes, and by adding hydrochlorate of lime to recent urine, washing the 

 precipitate and subsequent analysis. Recent healthy urine is always 

 acid ; but this state is not produced by carbonic acid, united to the 

 phosphates, as has been supposed. When salts of lead, lime, baryta, 

 or magnesia are added, the acidity is preserved unchanged. The car- 

 bonic acid usually present is disengaged by a powerful acid, with the 

 effervescence due to its gaseous form, but, independently of this, there 

 exists an acid reaction. It has been assumed that oxalic acid is absent 

 in cases where no crystals of oxalate of lime separated from samples 

 of urine preserved. If the acid action is very marked, such cases are 

 no exceptions, for in urine we do not expect unfailing chemical decom- 

 positions of salts. Besides, it can be shown that, even in alkaline urines, 

 oxalate of lime separates as red sand, and covers the surface after 

 several days of exposure for deposition. These, with other observa- 

 tions, lead to the conclusion, that we are far from possessing a true 

 knowledge of the composition of this important secretion. A true 

 analysis can only be made by operating on recent urine, by precipi- 

 tations and evaporations, without loss of time and aid of heat ; the 

 more important constituents are otherwise converted into secondary 

 products of the steps of the analysis." 



Professor Horsford read a paper from Mr. Breed of the Law- 

 rence Scientific School, giving an account of a series of ex- 

 periments on the nature of vesication, and showing that the 

 process was totally independent of evaporation. 



Professor Horsford also exhibited a Daguerreotype of the 

 moon, taken in front of the eye-glass of a telescope, by Mr. 

 Wells of the Scientific School. 



