Cottons known generally as Santos, Cæra and Pernams are not of this species—viz., Gossypium Peruvianum, but belong to the first and second of the types already described.
The Strength of Cotton Fibres.—Mr. O'Neill some years ago made many experiments with a view to obtaining the strengths of the different fibres, and the following table compiled by him, will be of interest to the general reader.
| Sea Islands | 83.9 | mean breaking strain in grains |
| Queensland | 147.6 | "" |
| Egyptian | 127.2 | "" |
| Maranham | 107.1 | "" |
| Bengueld | 100.6 | "" |
| Pernambuco | 140.2 | "" |
| New Orleans | 147.7 | "" |
| Upland | 104.5 | "" |
| Surat (Dhollerah) | 141.9 | "" |
| Surat (Comptah) | 163.7 | "" |
From this table it is arguable that the strength of fibre varies according to the diameter, that is to say, the fibre with the thickest diameter carries the highest strain. The order, therefore, in which the fibres would fall, according to strength, would be, Indian, American, Australian, Brazilian, Egyptian, and Sea Islands last.
The Chemistry of the Cotton Plant.—Messrs. M'Bryde & Beal, Chemists in the Experimental Station in Tennessee, say, "As a rule our staple agricultural plants have not received the thorough, systematic chemical investigation that their importance demands." It would appear that until recent times the above statement was only too true. Now, however, the United States Government and others have instituted experiments on a large scale, and everything is now being done in the direction of research, with a view to improving the quality of this important plant.
A complete Cotton plant consists of roots, stems, leaves, bolls, seed and lint. Now if these six parts of the plant be weighed, they vary very much, proving that some of them are more exhaustive than others, so far as the fertilizing matters found in the soil are concerned. For example, if water be discarded in the calculation, though this takes up a fair percentage of the total weight, about 10, it is found that the roots take up by weight over 8 per cent. of the whole plant, stems over 23 per cent., leaves over 20, bolls over 14, seeds over 23, and lint only 10½ per cent.
Now this statement is interesting as showing one or two important features. The weight of the seed is seen to be nearly a quarter of the whole plant, while the stems and leaves together take up nearly one half. A very small proportion by weight of the plant is taken by the lint.
A chemical analysis of the mature Cotton plant yielded the following substances:—
| Water. | Potash. | |
| Ash. | Lime. | |
| Nitrogen. | Magnesia. | |
| Phosphoric acid. | Sulphuric acid. | |
| Insoluble matter. |