II Gruener — Standard Solutions of Tartar Emetic. 207 



deposit, probably antim onions oxide; there was here a slight 

 loss in the strength of the solution, amounting to 1 per cent. 



Solution C was acid with tartaric acid only. After ten 

 months the solution was found of the same strength and clear- 

 ness as it was originally : but four months later there was a 

 slight deposit accompanied by a loss of 1*2 per cent. 



Parallel experiments to A gave like results. Two repeti- 

 tions of C with varying amounts of tartaric acid present 

 showed in each case a decided fungus growth with no loss of 

 strength at the end of five months, whereas at the end of nine 

 months the loss amounted to 1 per cent for the larger amount 

 of tartaric acid and 0'3 per cent for the smaller amount. 



It seems then that there is little danger of any oxidation of 

 the antimonious oxide occurring, and provided enough tartaric 

 acid is present to keep all the antimonious oxide in solution, 

 the solution should maintain its strength for at least five or 

 six months. The fungus growth has not been found to inter- 

 fere in practical work with the solutions, yet it seemed advisa- 

 ble to prevent its formation if it could be done simply. To 

 test the possibility of this, a number of solutions were pre- 

 pared containing varying amounts of hydrochloric acid, which 

 should act as a sterilizer ; enough tartaric acid was added to 

 counteract any tendency toward precipitation. In one series 

 of experiments the solutions were sterilized at the beginning 

 by boiling ; in the other series distilled water which had been 

 exposed more or less to the air for a number of days was 

 directly used. Where the solutions had been thus sterilized 

 no sign of fungus growth had appeared at the end of five 

 months, and in the case of the unsterilized solutions there was 

 never more than a trace. Where the hydrochloric acid present 

 was not more than 10 cm 3 to 500 cm 3 of water, there was at 

 the end of three months only the faintest trace of a deposit 

 and no material loss of strength. Where the hydrochloric 

 acid was present to the extent of 25 cm 3 in 500 cm 3 of water a 

 decided granular precipitate was observed, accompanied by a 

 loss of strength of about 10 per cent. The granular precipi- 

 tate dissolved in tartaric acid and titrated accounted almost 

 exactly for this loss. 



A number of solutions were prepared under varying condi- 

 tions and left open to the air for three months, at the end of 

 which time no loss from oxidation was found. 



It may be seen that tartar emetic in a solution of 16 grms. 

 to the liter is not oxidized either in closed or open bottles. If 

 it is desired to keep this solution as a standard for a moderate 

 length of time it can be done in presence of enough tartaric 

 acid (20 to 30 grms. to the liter) to prevent precipitation. 

 The addition of l cm hydrochloric acid to one liter of solution 



