622 
MESSRS. R. T. GLAZEBROOK AND S. SKINNER ON THE 
In June the portable cell No. 82 was sent by parcel post to London, and thence to 
Manchester, where it was compared by Dr. Schuster with his standards. About 
the same time No. 83 was taken to Manchester by one of us (R. T. G.) in a handbag. 
The cells were brought back to Cambridge in a portmanteau which travelled as 
passenger’s luggage. Dr. Schuster found that No. 82 was less than his standard by 
two of our units, while No. 83 was less by six units. The Table shows that on their 
return No. 82 had not changed relative to our standard, while No. 83 had varied 
considerably. Other comparisons confirmed these results. 
A large number of comparisons have been made from time to time between the 
large bottle cell, No. 90, and the standard. The two remain practically equal so long 
as the temperature remains steady for some time, but some experiments in March and 
April emphasize the importance of maintaining this very constant, at any rate, for 
large cells. 
Towards the end of March the weather was very cold. On March 30 the room 
temperature was 6°; it had been lower, and the baths in the room were as low as 
3 D, 5 : the cells were not examined at this date. On March 31, when the bath was at 
10°'8 C., No. 90 exceeded the standard by nine units. On April 1, the temperature 
being 11°‘2, the difference was five units. A rod was then put through a hole in the 
cork of the bottle cell, and the zinc sulphate was stirred up. The difference fell 
immediately to less than one unit, the temperature remaining unchanged. Thus, on 
March 31, the E.M.F of No. 90 corresponded to a temperature more than 2° below the 
temperature of the cell, and on April 1 it was still too high by an amount equivalent 
to the change due to 1 degree. The crystals had formed in a hard mass on the top 
of the paste ; the zinc was some little way above these, and the E.M.F remained too 
high until they were broken up. 
§ 31. Cells set up by Mr. E. H. Griffiths. 
In January and February of the present year, Mr. E. H. Griffiths set up a number 
of cells, following in the main the directions of the second issue of the Board of Trade 
Memorandum. These cells are numbered from 131 to 160. In one batch of these, 
No. 149 to 154, the zinc sulphate was treated with mercurous sulphate in the manner 
described on page 611. 
We give the description of these cells, kindly furnished to us by Mr. Griffiths, to 
whom our best thanks are due. 
Cells Nos. 131-142, made January 26, 1892. Chemicals supplied by Harring¬ 
tons. The ZnS0 4 was saturated at 33° C. The HguSO^ was used as supplied, except 
that it was shaken up with mercury, but not washed. 
Cells Nos. 143-148. January 31, 1892. The Board of Trade directions followed 
implicitly. 
Cells Nos. 149-154. February 6, 1892. To the ZnSG 4 solution saturated at 33° C., 
