A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c22.s4: Rust of Iron

A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c22.s4

Language: English

v1.c22.s4.t1 Sample I — 1 part
v1.c22.s4.t2 Sample II — 16 parts

Rust of Iron

Hindu physicians generally procure the scales from the black-smith’s forge, which peel off the red-hot bars of iron, when they are struck on the anvil with an iron hammer. These are subjected to further roasting, sometimes as many as 500 times and powdered very fine.

Sample I

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The powder was reddish brown in colour; and slightly magnetic; 0·6638 g was boiled a few hours with hydrochloric acid in a current of carbonic acid gas. On adding a drop of potassium ferricyanide solution to a drop of the iron solution, a faint blue colour was noticed. Weight of insoluble residue, which was simply siliceous matter, was equal to 0·107g; the oxide of iron was therefore equal to 0·6638g—0·107g.=0·5568g. The solution, distinctly yellow in colour, was treated with ammonia and the precipitate, ignited in the usual way, weighed 0·560 g. The sample was thus practically ferric oxide (Fe₂ O₃).

Sample II

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It was magnetic and of dark iron colour; 0·259g, digested as above with hydrochloric acid, gave as residue (sand &c.) 0·131 g, Wt. of the real oxide=128 g. The solution was treated with ammonia and the precipitate, ignited as usual, weighed 0·130 g. The latter was once more dissolved in HCl and tested with K₃ Fe Cy₆; but no indication of a ferrous salt was obtained. It is thus evident that both the samples contained only a trace of ferrous oxide.

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As a check upon the above analyses, black scales were procured from a smith's and examined. These were carefully sifted by means of an electromagnet and freed from dust and other foreign impurities. 0·622 g scales was heated in a platinum crucible over a blow-pipe flame and cooled at intervals, till the weight was constant at 0·649g.

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Now Fe O. Fe₂ O₃ thus becomes Fe O₃/2. Fe₂ O₃ or 232g ,, ,, ,, 240g

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Now 0·622 × 240/232 g = 0·643g

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The difference between the theoretical amount and that actually found is thus only 6 milligrams. This is no doubt due to the scales enclosing minute traces of metallic iron.

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In the Hindu method of killing and purifying metals, the juices expressed from various plants are frequently used (cf. pp. 61, 132). The ashes of plants rich in potash are also utilised as a source of alkali. (Cf. pp. 35-36). We give below one or two typical analyses.

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(i) *Achyranthes aspera* (अपामार्ग) ।

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"The ashes are used by the Hindus in preparing alkaline preparations. The diuretic properties of the plant are well known to the natives of India, and European physicians agree as to its value in dropsical affections.

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*Chemical composition.*—The whole plant collected in August was used. A proximate analysis failed to indicate the presence of any principle of special interest. No alkaloidal body was detected, and the alcoholic extract contained no principle reacting with ferric salts.

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"For the ash determination, the roots, stems and leaves were separately examined with the following results :—

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| | LEAVES. | STEMS. | ROOTS. |
| P₂O₅ . . . . . | 3·0257 | 2·6939 | 1·8504 |
| SiO₂ as Sand........ | 39·7192 | 12·9716 | 21·4219 |
| SO₃ . . . . . | 1·3200 | 2·6534 | 3·9523 |
| CaO . . . . . | 13·8893 | 13·1233 | 12·9335 |
| MgO . . . . . | 3·4778 | 3·5149 | 5·4419 |
| K₂O . . . . . | 17·8454 | 32·0008 | 28·5830 |
| Na₂O . . . . . | . . . . . | . . . . . | ·9860 |
| Fe₂O₃ . . . . . | 2·7931 | 3·0352 | 5·6297 |
| Manganese........... | Traces, not estimated. | Not estimated | Not estimated. |
| KCl . . . . . | 5·7416 | 9·5221 | . . . . . |
| NaCl . . . . . | 1·1770 | 1·5261 | 3·2951 |
| Al₂O₃ . . . . . | 2·0651 | Not estimated. | Not estimated. |
| CO₂ . . . . . | 8·8687 | 13·6294 | 11·0057 |
| Carbon . . . . . | ·3297 | ·5525 | Not estimated |
| | 100·2526 | 95·2232 | 95·1085 |

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"The leaves, stems, and roots dried at 100°C., afforded respectively the following percentages of ash,—Leaves, 24·334; stems, 8·672; roots, 8·863. The large amount of sand present in the ash is due to the fact of the plants having been collected during the rains, and when received they were coated with finely divided siliceous matter.

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"The total potash calculated as K₂O was equivalent in the leaves to 21·4986 per cent., in the stems to 38·0122 per cent., and in the roots to 28·5830 per cent. It is possible that the plant might be of value as a cheap green manure on account of potash content. (Warden, Chem. News, Vol. ii., 1891).”

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(ii) Juice of *Trianthema monogyna* (श्वेतपुनर्नवा)

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Although *Punarnava* is *Boerhaavia diffusa*, the plant universally used by our *Kavirajes* as श्वेतपुनर्नवा, is different. A sample was submitted to the authorities of the Royal Botanical Gardens, Sibpur, for examination, and it was indentified as *Trianthema monogyna* (nat. ord. Ficoideæ). On chemical analysis of the juice of the succulent stems, we found it to consist of a large proportion of potassium and sodium chlorides; a nitrate was also detected. The cooling and diuretic properties of the plant are thus easily explained.

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