A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c21: On the Hindu Method of Manufacturing Calomel; The Hindu and Japanese Methods Compared—The Explanation of the Reactions Involved
A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c21
- Language
- English
On the Hindu Method of Manufacturing Calomel; The Hindu and Japanese Methods Compared—The Explanation of the Reactions Involved
v1.c21.1
According to the Hindu alchemists, there are four kinds of the ash (*bhasma*) of mercury, namely black (*kajjali*, p. 61), red (vermilion), white and yellow.¹ The white variety is often spoken of as rasakapūra or camphor of mercury; it is often found to be almost pure calomel and sometimes a mixture in indefinite proportions of calomel and corrosive sublimate.
v1.c21.2
¹ कृष्णभस्म, रक्तभस्म or रससिन्दूर; श्वेतभस्म and पीतभस्म Vide—रसेन्द्रसारसंग्रह: what the yeilow ash refers to is not easy to make out.
v1.c21.3
The chlorides of mercury are found to be medicinally used from the 12th century downwards and various recipes are given for their preparation. The earliest account seems to occur in Rasārnava (ch. XI. 24), where we find a mixture among other drugs of green vitriol, alum and salt, described as capable of "killing mercury in an instant" (see p. 73). A more detailed description is found in "Rasendrachintāmani" a work which may safely be placed in the 13th-14th century. Says the author Dhundhukanātha : "I am now going to explain the process of preparing rasakarpūra, which is a remedy for all diseases: take a strong earthen pot and fill one-fourth of it with common salt and place over it a mixture of brick-dust, alum and rock-salt. Rub mercury with the juice of Indian aloe and an equal weight of the above mixture into a paste; deposit it in the earthen pot and cover it with the same ingredients. The pot is to be firmly closed with a well-fitting lid. Now apply heat for three days together." ¹
v1.c21.4
(1) सर्वरोगहरी कर्पूरप्रक्रिया स्थायां दृढघटितायामङ् परिपूर्य तुर्यलवणंशैः । रक्तष्टकारजोभिसदुपर् सूतस्य तुर्यांशम् ॥ सितसैन्धवं निधाय स्फटिकारीं तत्समञ्च तयोर्द्वे । स्फटिकारिसधैसैन्धवगुडरसैः कन्याम्बुपरिघष्टैः ॥ कृत्वा पर्पटमुचितं तदुपर्याधाय तद्देव पुनः । स्फटिकारिसैन्धवरजो दद्यादितः खल्लतो रसस्य ॥ लाभाय तदुपरि पर्परखण्डान् धृत्वा परया । दृढस्थाल्ल्याच्छाद्य मुद्रयित्वा दिवसत्रितयं विपचेद्विधिना ॥
v1.c21.5
Another work of the Iatro-chemical period, "Rasendrasārasamgraha" describes the following process for obtaining the *svetabhasma* or white ash. "Rub mercury repeatedly with *pāmsu* salt (i. e. audbhida salt : see p. 243) and the juice of *Euphorbia neriifolia*; place the mixture inside an iron bottle, the mouth of which is closed with a piece of chalk. The bottle is embedded in a mass of salt (cf. the salt-bath, p. 123) and then fire is urged for an entire day. The white deposit in the neck of the bottle is to be collected."¹
v1.c21.6
¹ > पिष्टं पांशुपटु प्रगाढममलं वज्रांबुना नैकशः
v1.c21.7
The Bhāvaprakāsa written about 1500 A. D. prescribes calomel in the treatment of *Phirangaroga* (lit. the disease of the Portuguese i. e. syphilis) and gives the following recipe: "Take of purified mercury, *gairika* (red-ochre), brick-dust, chalk, alum, rock-salt, earth from ant-hill, *kshāri lavana* (impure sulphate of soda) and *bhāndaranjika* or red earth used in colouring pots in equal parts, rub together and strain through cloth. Place the mix-
v1.c21.8
सूतं धातुगतं खटीकवलितं तं संपुटे रोधयेत् ।
अन्तल्लवणस्य तस्य च तले प्रज्वाल्य वह्निं दृढं
घसं ग्राह्यमथेन्दुकुन्दधवलं भस्मोपरिस्थं शनैः ॥
v1.c21.9
true in an earthen pot, cover it with another pot, face to face, lute the two together with layers of clay and cloth. The pots so luted are then placed on fire, and heated for four days, after which they are opened, and the white camphor-like deposit in the upper part is collected for use."¹
v1.c21.10
शुद्धमृतसमं कुर्यात्प्रत्येकं गैरिकं सुधीः ।
इष्टकां खटिकां तद्वत्स्फटिकां सिन्धुजं च ॥
वल्मीकं क्षारलवणं भाण्डरञ्जकमृत्तिकाम् ।
सर्वाण्येतानि सञ्चूर्ण्य वाससा चापि शोधयेत् ॥
एभिःस्र्ैर्युतं सूतं यावद्यामं विमर्दयेत् ।
तच्चूर्णसहितं सूतं स्थालीमध्ये परिचिपेत् ॥
तस्याः स्थाल्या मुखे स्थालीमुपरां धारयेत्समाम् ।
सवस्त्रकुटितमृदा मुद्रयेदनयोर्मुखम् ॥
संशोष्य मुद्रयेद्भूयः संशोष्य मुद्रयेत् ।
सम्यग्विशोष्य मुद्रां तां स्थालीं चुल्ल्यां विधारयेत् ॥
अग्निं निरन्तरं दद्याद्यावद्दिनचतुष्टयम् ।
अङ्गारोपरि तद्यन्त्रं रचेद्यद्वादहर्निशम् ॥
शनैरुद्घाटयेद्यन्त्रं मूर्द्धस्थालीगतं रसम् ।
कर्पूरवत्सुविमलं गृह्णीयाद्गन्धवत्तरम् ॥
v1.c21.11
The Japanese method has been described by Professor Divers at length¹ and a summary of it is given below in the eminent chemist's own words :—
v1.c21.12
“The Japanese prepare calomel pure, above all things from corrosive sublimate. They heat balls of porous earth and salt soaked in bittern along with mercury, in iron pots lined with earth. The heat forms hydrochloric acid from the magnesium chloride in the bittern, and the mercury sublimes into the close-fitting but unattached clay covers of the pots. Air enters by diffusion and oxygen and hydrochloric acid gas act together in the hollow cover on the vapour given off from the sublimate of mecury there formed.”
v1.c21.13
It will be seen that the process somewhat approaches that of “Rasendrasārasamgraha” in which the pāmsu salt, which contains magnesium sulphate (see p. 252) sets free hydrochloric acid. The recipe of “Rasendrachintāmani” and Bhāvaprakāsa would seem to have their analogue in the Chinese method, for a short account of which we are also indebted to Professor Divers' Memoir :—
v1.c21.14
The translation from “Bhāvaprakāsa” as given above is by Dutt.
v1.c21.15
(1) “Journ. Sec., Chem. Ind.” Vol XIII. (1894) pp. 108-11.
v1.c21.16
"The Chinese process, if correctly described, differs from that used in Japan in several material points, one of which is that the mercury is intimately ground up with the other materials, and one fails to see what reaction can take place between it and the two others, namely salt and alum. Heated, the mixture must give off mercury and hydrochloric acid, and then these, as in the Japanese process, will with air give the calomel, but this is independent of the previous intimate mixture of the mercury with the salt and the alum. Another point is that in place of the magnesium chloride of sea-water as the source of hydrochloric acid, the Chinese are said to use alum or copperas, which, with the salt, will react to give hydrochloric acid. A third point is that the cover is said to be closely luted to the iron pot, which must nearly exclude the air, without which it is impossible to explain the formation of calomel. Perhaps this is the reason why the Chinese process is said to take four or five hours' firing, since this may give time enough for the needed oxygen to diffuse through the cup and luting, it will also account for the fact, if it is one, that the yield of calomel is markedly less in weight than the mercury used."
v1.c21.17
The Chinese and Hindu methods¹ are essentially the same as in both alum plays an important part in that it yields sulphuric acid. Professor Divers in his explanation of the Japanese method supports the view that the hydrochloric acid at first liberated undergoes aerial oxidation, thus: 2HCl + O = H₂O + Cl₂; and it is the chlorine thus set free, which attacks the mercury, forming calomel—a view which has been accepted by no less an authority than Mendeléeff.² The author has all along entertained doubts as to the correctness of Divers' hypothesis and he has, in his lectures, pointed out to his students that some "catalytic agent" as in Deacon's process must account for the reaction involved. This now turns out to be so. It is the *ferric*
v1.c21.18
(1) To which may be added that of the Latin Geber :—
v1.c21.19
"Argentum vivum sic sublima. Sume de eo libram unam, vitrioli rubificati libras duas, aluminis rochae calcinati libram unam, et salis communis libram semis, et salis petrae quartam partem, et incorporatum sublima, et collige album, densum, clarum et ponderosum, quod circa vasis sponditia inventum fuerit, et serva, ut tibi de aliis scripsimus. Sed si in prima sublimatione inventum fuerit, turbidum vel immundum, quod tibi accidere poterit propter tuam neglegentiam, illud cum eisdem fecibus noveris iterum sublimare, et serva."—"Ges. d. Chem." IV. p. 189.
v1.c21.20
2) "Principles of Chemistry," Vol. II. p. 54 (Eng. trans. ed. 1897).
v1.c21.21
oxide, a constituent of the burnt earth “*mitsuchi*”¹ which really acts as the chlorinating agent, if we may so call it, in that it combines with the hydrochloric acid forming ferric chloride, and the latter in turn dissociates into *ferrous chloride* and *free chlorine*.
v1.c21.22
¹ The composition of the earth, as found in use at the works, but rendered anhydrous, is as follows :—
v1.c21.23
The alumina of the clay also plays a similar part. A series of experiments were undertaken to establish this point, the results of which are stated below :—
v1.c21.24
I. Mercury, intimately rubbed with moist magnesium chloride, was gently heated in a combustion tube in a current of carbonic acid gas : globules of mercury and hydrochloric acid condensed in the cooler parts of the tube, but no calomel was formed.
v1.c21.25
II. Mercury, intimately mixed with magnesium chloride and a small quantity of jeweller’s *rouge*
v1.c21.26
| Quartz | ... | ... | 38·4 |
| Combined Silica | ... | 24·2 | |
| Alumina | ... | ... | 26·3 |
| Ferric oxide | ... | ... | 10·5 |
| Magnesia | ... | ... | 0·3 |
| | | | —— |
| | | | 99·7 |
v1.c21.27
(ferric oxide), was treated exactly as above—a crystalline sublimate of calomel was at once obtained, with only a faint trace of corrosive sublimate. There was very little free mercury left.
v1.c21.28
III. The experiment under ii was repeated, only alumina being substituted for ferric oxide—almost chemically pure calomel was obtained, the yield being rather less.
v1.c21.29
IV. Mercury, was vapourised in a current of air mixed with hydrochloric acid gas—calomel was formed, but the yield was proportionately very much less than in i; by far the largest amount of mercury volatilised as such and condensed in the cooler parts of the tube as globules.¹
v1.c21.30
¹ The author avails himself of this opportuntiy to express his indebtedness to Mr. Chandrabhúshana Bhádurí, B.A., Demonstrator, Chemical Dept., Presidency College, with whom he has, of late, had frequent discussions on the chemistry of the Japanese Process. It was Mr. Bhádurí who hit on the true explanation as given above. The experiments i, ii, iii and iv were all performed by him. As Mr. Bhádurí has expressed a desire to work out the subject in all its bearings, we can confidently look forward to some very interesting results.
v1.c21.31
The formation of calomel as in exp. IV. is, in itself, an interesting reaction and it is rather surprising that Roscoe and Schorlemmer's latest edition of the standard work on Chemistry fails to take note of it. Our contention, however, is that the traces of air that would diffuse through the porous lid would give rise to a quantity of calomel which may almost be regarded as negligible. For the true explanation, as we have already pointed out, we should look to the presence of *ferric oxide*. Our view receives additional support from the fact that the residue in exp. ii. was found to contain *ferrous chloride*.
v1.c21.32
The Chinese method as also that of the Latin Geber recommends the addition of saltpetre as thereby more of corrosive sublimate would be formed than calomel, and this purpose is equally served in the process of Bhāvaprakāsa which uses, over and above brick-dust, *gairika* (red ferruginous earth, see p. 139, thus further increasing the chlorinating capacity. Professor Divers is of opinion that the sulphuric acid set free by alum acts upon sodium chloride giving rise to hydrochloric acid (loc. cit). and does nothing more; our view is that the sulphuric acid simultaneously acts in a two-fold capacity; first, it liberates hydrochloric acid; secondly, it acts upon mercury forming mercurous or mercuric sulphate as the case may be and then double decomposition takes place between the two thus:
v1.c21.33
Hg₂ SO₄ + 2HCl=Hg₂ Cl₂ + H₂ SO₄
v1.c21.34
The sulphuric acid in turn acts upon a fresh quantity of sodium chloride and mercury and so on. By far the larger portion of the chlorides of mercury would seem, however, to be formed through the agency of the ferric oxide.
v1.c21.35
The processes of "Rasendrachintāmani" and "Bhāvaprakāsa" were also put to an experimental test, the globules of mercury were broken up by being rubbed continuously with a mixture of brick-dust, alum and common salt, and the mass was transferred to a stout bottle, which was wrapped in several folds of cloth, smeared with clay¹. The bottle was embedded in sand and heated for 3 hours²—vide illustration. The sublimate that was obtained was a mixture of calomel and mercuric chloride; in one experiment brick-dust was omitted and the product was pure calomel¹. There was necessarily some loss of mercury by volatilisation in these cases and the yield was short of the theoretical quantity. It will be seen that common salt, with alum or green vitriol, is quite competent to convert mercury into calomel; but the addition of brick-dust increases the chlorinating capacity, giving rise to a certain proportion of corrosive sublimate, which can probably be avoided by gentle heating as in the Japanese method.
v1.c21.36
¹ The experiments were conducted under the author's personal supervision by Kaviráj Prakritiprasanna Kaviratna, who is well skilled in the Hindu methods of killing metals.
v1.c21.37
² The heating for 3 or 4 days together as recommended in the Hindu method need not be taken seriously, indeed it must be regarded as an extravaganza of the old alchemists. Professor Divers in applying his theory of ærial oxidation to the Chinese process has been led to suppose that it "takes 4 or 5 hours' firing, since this may give time enough for the needed oxygen to diffuse through the cup and luting."
v1.c21.38
¹ Dutt writes :—"The white form called *rasakarpūra* is now prepared, not according to the processes described in Sanskrit works, but by subliming the black sulphide of mercury with common or rock salt. In this form it is largely manufactured and sold in all the bazars."
Linked texts (4)
- Rasārṇava — Sanskrit
- Rasendracintāmaṇi — Ḍhuṇḍhukanātha, Sanskrit
- Bhāvaprakāśa — Bhāvamiśra 1550, Sanskrit
- Rasendrasārasaṃgraha (Gopāla Kṛṣṇā) — Gopāla Kṛṣṇā 1800, Sanskrit