[Proc. Roy. Soc. Victoria, 30 (N.S.), Pt. II., 1918]. 



Art. X. — A Method of Eslhnating Small Amounts of Calcium. 



By S. pern, M.R.C.S., L.R.C.P. Eng. 



(Communicated by Professor W. A. Osborne). 



[Read 13tli September, 1917]. 



Yov long there has been need of a simple and easy method of 

 estimating small quantities of calcium, such as would be useful in 

 clinical medicine. 'After some 'four years' experimenting the 

 following method was found to l>e the most useful : — 



To a slightly acid solution containing a soluble calcium salt, from 

 three-quarters to an equal volume of methylated spirits is added 

 without mixing, then a few drops of a saturated solution of oxalic 

 acid, and the whole shaken up, almost immediately a white clou<l 

 appears. 



The addition of small quantities of alcohol hastens the forma- 

 tion of calcium oxalate deposit, but on putting some of this white 

 precipitate under the ultra-microscope no crystalline shape is 

 observed, but small rounded masses about O.l^x in diameter, and 

 comparing them with a typhoid bacillus it was estimated it would 

 take 128 to make up the same size. 



In estimating the calcium content of the blood a small glass 

 tube is marked to 1 c.c. content, and blood is drawn from a vein 

 with a hypodermic syringe, and immediately transferred to the 

 tulje up to the 1 c.c. mark. This is placed at leisure in a platinum 

 crucible, using a little distilled water to wash out the tube; the 

 wash water is also transferred to the crucible. It is then passed 

 to and fro through a strong flame, and with practice one is able to 

 burn the blood to a black ash without any bubbling over or splut- 

 tering, which is inevitable if it is dried off first. It has also the 

 advantage of being rapid. It is then placed in a small electric 

 furnace, which is already at a dull red heat, and left there till 

 thoroughly ashed, about half an hour being ample. During the 

 ashing, controls and filter papers are prepared. 



For the nephelometric method the writer uses glass tubes of an 

 even bore with flat bottoms about 8 cm. long and marked in 1 c.c. 

 gradations. Total capacity would be about 8 c.c. Double filter 

 papers are used 4 cm. in diameter and very small glass funnels. 

 The filter-papers are rinsed through with 4 c.c. of 2 per cent, 

 acetic acid, which is found sufficient to eliminate all traces of 

 soluble Ca from them. This is necessary, as Mr. H. Lyman 



