THK NEW YORK JOURNAL OF PHARMACY 



used to deliver the 20 drops of distilled 

 water at 15° C. to weigh one gram. The 

 firm of Greiner & Co. furnished a 

 burette according to our directions — 20 

 cc. burette accurately graduated in 

 tenths, 3 mm. in diameter for dropping 

 surface delivering 20 drops of water to 

 weigh one gram at 15° C. Upon testing 

 the burette was found to be exact pro- 

 vided a certain rate of dropping was 

 maintained. The difference in weight 

 of the drop due to a changed rate of 

 dropping amounted to about i to 2 milli- 

 grams per drop. 



In order to maintain the temperature 

 during the process of dropping, the 

 burette was jacketed and water cooled 

 to 15° C, passed through it. A ther- 

 mometer was suspended in the burette. 

 The accompanying sketch illustrates the 

 apparatus used. 



By means of this apparatus a large 

 number of drop weights of the more 

 common potent medicines were deter- 

 mined and were found in most instances 

 to agree closely to those determined by 

 Dr. Frederich Eschbaum. Eschbaum 

 was the first scientist to advance definite 

 maxims relative to drop weights which 

 maxims are interesting as well as im- 

 portant and we can only, confirm the 

 accuracy of such as we had occasion to 

 try out. They are : First, the drop 

 weights of solutions, even of the most 

 concentrated ones, are practically equal 

 to those of the solvent. 



To cite an example, an aqueous 50 per 

 cent, potassium iodide solution will have 

 almost the same drop weight as pure 

 water and aqueous solutions of alka- 

 loids, sugar, salts, extracts or gums have 

 the drop weight of water. Alcoholic 

 tinctures have the drop weight of alcohol. 



b - Water- Jocf'^i^ 



C - i^rsr- In/er f^^ Cooler 



d - WaOr Outler 



ApMHATUS ^ 



Duop-ln/ciariT Dctlrminatioh 



Second, different liquids have different 

 drop weights. The authors of this paper 

 believe that the drop weight can be used, 

 to a certain extent at least, to help in the 

 identification of certain pure liquids and 

 preparations. 



Third, the drop weight depends upon 

 the size of the dropping surface. The 

 standard for this is 3 mm. 



Fourth, Eschbaum states that the rate 

 of dropping as well as temperature may 

 be neglected for practical purposes. The 

 authors find that it is quite necessary to 

 preserve the temperature carefully and 

 also to maintain a standard rate of drop- 

 ping to get accurate results. 



A number of drop weights of some of 

 the more important medicines, as deter- 

 mined by Mr. Roon and bearing out the 

 above statements, is appended. 



