One of the specimens (a) was described as
“Natural lard; iodine value, 57.1. Leaf lard used exclusively for butterine and benzoinated lard.”
The other specimen was described as
“Prime steam lard. Good, commercial grade of lard for general use; iodine value, 69.0.”
The iodine absorption numbers of the three specimens were determined by the U. S. P. process to be as follows:
| Laboratory rendered specimen | 57.1 |
| Armour specimen (a) | 57.65 |
| Armour specimen (b) | 67.55 |
Each specimen was benzoinated according to the process described in the U. S. P. IX and 100 gm. of iodine ointment were prepared from each according to the U. S. P. process. Another specimen was made from benzoinated lard and iodine only[194] without the addition of either glycerin or potassium iodide. This was made to contain 4 per cent. of iodine.
Immediately after preparation each of these iodine ointments was assayed for free iodine, and each was reassayed at intervals later. The method for the determination of iodine in the ointment was that employed in this laboratory for the determination of iodine in Iocamfen Ointment.[195] It is essentially the same as was employed by Pullen for the determination of uncombined iodine in iodine ointment.[196] As carried out in this laboratory for iodine ointment it is as follows:
From 5 to 8 gm. of the ointment were weighed in a small porcelain capsule, the capsule and contents placed in a 16 oz. salt mouth bottle together with 20 c.c. of chloroform, 10 c.c. of potassium iodide solution and 40 c.c. of water. Tenth-normal sodium thiosulphate was slowly added with agitation until the pink color of the chloroform layer had nearly disappeared. A little soluble starch was then added and the titration continued until a blue color in the aqueous layer could no longer be obtained by repeated shaking.
The findings for the several assays are tabulated herewith: