52 JOURNAL OF THE 



NEW AND IMPROVED METHODS OF ANALYSIS. 



BY S. J. HINSDALE. 



COLORIMETRIC METHOD FOR ESTIMATING THE MORPHINE 

 STRENGTH OF LAUDANUM AND OTHER PREPA- 

 RATIONS OF OPIUM. 



Prepare an officinal tincture of opium with assayed opium. 

 You will know the morphine strength of this tincture. 

 Make tliree dilutions of it with dilute alcohol, as follows: 



One 3 parts tincture and 1 pari dilnte alcohol. 

 One 2 " " " 2 " " " 



One 1 •' " " 3 " 



Put 12 cc. of the tincture and of the dilutions in vials, 

 and add to each 12 cc. dihite alcohol — cork well and keep 

 them as standard dilutions of known strength. L-»bel them 

 Nos. 1, 2, 3 and 4. Let the dilute officinal tincture be No. 1. 

 Dissolve 0.04 gram potassic ferridcyanide in 500 cc. water, 

 and add to it fifteen drops liquor ferri chloridi. Call this 

 Ferridcyanide Mixture. {This must be freshly prepared). Pre- 

 pare it in a glass-stoppered bottle, with water perfectly free of 

 iron. 



Place four 50 cc. clean glass tumblers or wine-glasses on a 

 white surface, and deliver with a pipette (about one-third filled) 

 one dro[) of the dilutions in the glasses, commencing with No. 4 

 (the weakest), blowing out the pipette after each dropping. 

 (The pi})ette should be about four inches long, and made of one- 

 quarter inch tubing, and should deliver drops of the dilutions 

 weighing about .016 gram or one-fourth grain. To test the 

 pipette, see how many drops will balance a .200 gram weight. 

 The reason for using so small a drop, and for diluting the tinc- 

 ture, is because a full drop of the undiluted tincture would 

 develop too deep a blue color). 



Now add to each glass about 5 cc. ferridcyanide mixture 

 (it is convenient to use a homeopathic vial as a measure), and in 



