Pond. — On Citric Add ohtained from Auckland and Tahiti Limss. 405 



Aet. LXVII. — On the Percentage of Citric Acid ohtained from Limes grown 

 in Auckland and Tahiti. By J. A. Pond. 

 [Read before the Auckland Institute, 15th November, 1881.] 

 In the course of my analytic duties I have frequently had to examine samples 

 of lime-juice from the Pacific Islands, many of these samples being adulte- 

 rated with fresh or sea-water. When making these examinations I have 

 often felt the need of a standard sample with which to compare those I had 

 to investigate, the only reports I had access to being those of West Indian 

 and Sicilian juice. 



Through the kindness of Captain Sinclau*, of the schooner " Sybil," I 

 received a box of fine ripe limes in April last, each fruit being carefully 

 wrapped in paper. Of these I took forty, weighing 5 lbs. 12 ozs., and care- 

 fully grated off the skins, the weight then being reduced to 5 lbs. 4 ozs. 

 These I submitted to expression, the result being forty fluid ounces, or a 

 little more than 50 per cent, of the weight of the pulp, though a much larger 

 return would be obtained with suitable power. The juice thus obtained was 

 of a light sherry colour, cloudy, and of a specific gravity of 1-0412 at 62° 

 Fahr. The ash I found a percentage of '845, and its acidimetric value to be 

 7*752. About the same period I also received a parcel of limes from the 

 Hon. F. Whitaker, grown on his land at Lake Takapuna. These hmes were 

 very much smaller than those from the Islands. Taking ninety I had them 

 carefully peeled, and found the weight to be exactly 4 lbs, from which- 1 

 expressed twenty fluid ounces of juice, still leaving a good deal in the marc, 

 which would be obtained with greater power. The specific gravity of this 

 juice at 62° Fahr. was 1-0454, the percentage of ash '627, and its acidi- 

 metric value 8-13. 



These values compare very favourably with those of European reputa- 

 tion, and are as follows : — 



Specific gravity of juice 

 Per cent, of citric acid . . 

 Percent, of ash. . 



Palermo. W. Indian. Jamaican. S. African. Tahitian. N. Zealand, 



1044-85 

 8-13 

 •289 



1041-30 

 7'96 

 •321 



1044-18 

 8-66 

 •401 



1044-90 

 8-50 

 -364 



1041-20 

 7-75 

 -845 



1045-40 

 8-13 

 •627 



When we consider that the lime grows well here, and fi'om this to the 

 North Cape, it will be seen to what advantage this tree might be cultivated. 

 Eequiring little care in the raising, and fruiting abundantly, for a large por- 

 tion of the year the crop would be of magnitude, and the yield of juice with 

 a suitable press would be fully fifty per cent. For lime-juice there is always 



