Messrs. Chapman of Newcastle, to whom the art of rope-making is deeply indebted, having observed that rope yarn is considerably weakened by passing through the tar-kettle, that tarred cordage loses its strength progressively in cold climates, and so rapidly in hot climates as to be scarcely fit for use in three years, discovered that the deterioration was due to the reaction of the mucilage and acid of the tar. They accordingly proposed the following means of amelioration. 1. Boiling it with water, in order to remove these two soluble constituents. 2. Concentrating the washed tar by heat, till it becomes pitchy, and then restoring the plasticity which it thereby loses, by the addition of tallow, or animal or expressed oils.
In 1807, the same able engineers obtained a patent for a method of making a belt or flat band, of two, three, or more strands of shroud or hawser-laid rope, placed side by side, so as to form a band of any desired breadth, which may be used for hoisting the kibbles and corves in mine-shafts, without any risk of its losing twist by rotation. The ropes should be laid with the twist of the one strand directed to the right hand, that of the other to the left, and that of the yarns the opposite way to the strands, whereby perfect flatness is secured to the band. This parallel assemblage of strands has been found also to be stronger than when they are all twisted into one cylinder. The patentees at the same time contrived a mechanism for piercing the strands transversely, in order to brace them firmly together with twine. Flat ropes are usually formed of hawsers with three strands, softly laid, each containing 33 yarns, which with four ropes, compose a cordage four and a half inches broad, and an inch and a quarter thick, being the ordinary dimensions of the grooves in the whim-pulleys round which they pass.
Relative Strength of Cordage, shroud laid.
| Size. | Warm Register. | Cold Register. | Common Staple. | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tons. | Cwt. | Qrs. | Lbs. | Tons. | Cwt. | Qrs. | Lbs. | Tons. | Cwt. | Qrs. | Lbs. | |||
| 3 | inches bore | 3 | 17 | — | 16 | 3 | 5 | 3 | 16 | 2 | 9 | 1 | 24 | |
| 3 | 1⁄2 | — | 5 | 5 | — | — | 4 | 9 | 2 | 21 | 3 | 6 | 1 | 27 |
| 4 | — | 6 | 17 | — | 16 | 5 | 17 | — | 4 | 4 | 5 | 3 | 7 | |
| 4 | 1⁄2 | — | 8 | 13 | 2 | 8 | 7 | 5 | 3 | 1 | 5 | 1 | 2 | 6 |
| 5 | — | 10 | 14 | 1 | 4 | 9 | 3 | — | 4 | 6 | 9 | 2 | 8 | |
| 5 | 1⁄2 | — | 12 | 19 | 2 | 4 | 11 | 1 | 1 | 25 | 7 | 12 | — | 22 |
| 6 | — | 14 | 15 | 2 | 24 | 13 | 3 | 2 | 8 | 8 | 17 | 1 | 20 | |
| 6 | 1⁄2 | — | 18 | 2 | — | 10 | 15 | 9 | 1 | 9 | 9 | 16 | 3 | 14 |
| 7 | — | 21 | — | — | — | 17 | 18 | 3 | 8 | 11 | 4 | 1 | 21 | |
| 7 | 1⁄2 | — | 24 | 2 | — | 16 | 20 | 11 | 3 | 9 | 12 | 8 | 3 | 6 |
| 8 | — | 27 | 8 | 1 | 26 | 23 | 8 | 2 | 8 | 13 | 2 | 3 | 12 | |
The above statement is the result of several hundred experiments.
ROSIN, or COLOPHANY (Galipot, Fr.; Fichtenharz, Germ.); is the rosin left after distilling off the volatile oil from the different species of turpentine. Yellow rosin contains some water, which black rosin does not. See [Turpentine].
ROSIN GAS. [Fig. 952.] exhibits the retort and its appendages, as erected by Messrs. Taylor and Martineau, under the direction of the patentee, Professor Daniel, F.R.S.
I have introduced this manufacturing project, not as a pattern to imitate, but as an example to deter; as affording a very instructive lesson of the danger of rushing headlong into most extensive enterprises, without fully verifying, upon a moderate scale, the probability of their ultimate success. The capital, labour, and time annually wasted upon visionary schemes of this sort, got up by chamber chemists, are incalculably great. No more essential service could be rendered to the cause of productive industry, than to unmask the thousand and one chimerical inventions which disgrace our lists of patents during the last thirty years. These remarks have been suggested by the circumstance, that 50,000l. were squandered upon the rosin-gas concern; a fact communicated to me by an eminent capitalist, who was induced by fallacious statements to embark largely in the speculation. Had 100l. been employed beforehand, by a dispassionate practical man, in making judicious trials, and in calculating the chances of eventual profit and loss, it would have been demonstrated, as clearly as noonday, that rosin could never compete with pitcoal in the production of gas-light. Whatever ingenuity was expended in getting up the following apparatus, may be regarded as an additional ignis fatuus to mislead the public, and divert their thoughts from the abyss that lay before them. The main preliminary to be settled, in all new undertakings, is the soundness of the principle. By neglecting this point, projectors perpetually realize the expiatory fable of the Danaïds.
