1865.] Double Chlorides and Oxalates. 149 



the weaker the solution of this chloride is, provided only it is of sufficient 

 strength to combine with the oxalate, the larger will he the crystals of the 

 double salt. 



Since writing the above I find that the same double compound of 

 oxalate of lime and chloride of calcium has been prepared by Fritsche by a 

 different process. 



Not having formed the double salts of oxalate of magnesia and oxalate 

 of baryta with their respective chlorides on the larger scale, I am not able 

 to give any special directions as to the easiest method of preparing them in 

 large quantities ; but from what has been stated concerning the micro- 

 scopical processes, the mode of preparing them in such quantities is 

 obvious. 



Of the general properties of the double salt of oxalate and chloride of 

 strontium, I may observe that it is very slightly soluble in the solution in 

 which it is prepared, but rather more so in the hot than in the cold solu- 

 tion. It can be deprived in a great measure of the fluid in which it was 

 formed, by pressure between sheets of blotting-paper : it is neither deli- 

 quescent nor efflorescent. It is decomposed by water into oxalate and 

 chloride, but it is not at all affected by absolute alcohol, being entirely in- 

 soluble therein ; hence this medium can be employed in freeing the salt 

 from any adherent chloride : to effect this, the washing with absolute 

 alcohol must be done by decantation, and not on a filter, as during the eva- 

 poration of the alcohol a small quantity of water is deposited from the 

 air, which would decompose some of this compound salt, and, the chloride 

 of strontium being soluble in alcohol, some oxalate would be left in excess. 

 For the analysis of this salt I am indebted to the kindness of Mr. Holmes, 

 Dr. Gladstone's assistant, and Mr. Tribe of St. Thomas's Hospital. 



The following is the formula deduced from the subjoined analysis of Mr. 

 Holmes : 



2 Sr 2 O 4 . 2Sr Cl . 2H 2 O . 4Aq. 



Experiments. I. II. Theory. 



Oxalate of strontium 39'53 39'63 39'58 



Chloride of strontium 36'02 35-59 35'80 



Water, fixed at 100 C 8-11 8'25 8-18 



Water, given off at 100 C. .. 16-34 16-53 16-44 



100-00 100-00 100-00 



which agrees with that deduced by Mr. Tribe. 



Besides this there is another compound of oxalate of strontia and chlo- 

 ride of strontium, consisting of different proportions of these constituents, 

 which can be prepared in the following manner : To well- formed crystals 

 of the above salt, contained in two or three times their weight of saturated 

 solution of chloride of strontium, add gradually, and at intervals of two or 

 three hours, a mixture of equal parts of saturated solution of chloride of 

 strontium and water, until by examination with the microscope the greater 



