Art. LXVII.—On the Percentage of Citric Acid obtained from Limes grown in Auckland and Tahiti.
[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 adulterated 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 Sinclair, 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 carefully 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 limes 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 I 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 acidimetric value 8.13.
These values compare very favourably with those of European reputation, and are as follows:—
[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]
|Palermo.||W. Indian.||Jamaican.||S. African.||Tahitian.||N. Zealand.|
|Specific gravity of juice||1044.85||1041.30||1044.18||1044.90||1041.20||1045.40|
|Per cent. of citric acid||8.13||7.96||8.66||8.50||7.75||8.13|
|Per cent. of ash||.289||.321||.401||.364||.845||.627|
When we consider that the lime grows well here, and from this to the North Cape, it will be seen to what advantage this tree might be cultivated. Requiring little care in the raising, and fruiting abundantly, for a large portion 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
a fair demand, while a large production would certainly warrant the erection of a factory in some central place for the manufacture of citric acid, an article always so largely and steadily in demand in all parts of the world as to remove any danger of sharp competition reducing its value.
If, in addition to the Citrus limetta and C. limonum the C. bergamia was also planted, the essential oil, which could be extracted by machinery at a very small cost, would also add to our list of exports, while the juice would be of value in the manufacture of citric acid. The position of Auckland in respect to the Island trade, and to the extent of land to the north so well adapted to the growth of this species, points to a successful industry in the manufacture of citric acid in this city at no very distant date.