1. In these petitions under Article 226 of the Constitution, the petitioners have prayed for quashing the assessment orders levying sales tax on their sales of kala namak.
2. Section 4 of the U. P. Sales Tax Act, 1948 (hereinafter called the Act), has exempted from sales tax certain goods. One of them is salt. In Commissioner, Sales Tax, U.P. v. Balwant Singh Jag Roshan Lal  26 S.T.C. 129, a Division Bench of this Court held that "black salt" is included in the word "salt" occurring in Section 4(l)(a) of the Act and hence is exempt from U.P. sales tax. The above decision was rendered on 18th February, 1970. On 1st December, 1973, the Government of Uttar Pradesh issued a notification in exercise of its powers under Sub-section (2) of Section 3-A of the Act providing that the turnover in respect of the goods set out in the schedule thereto shall be liable to tax at all points of sale at the rate specified against each in column III of that schedule. The relevant portions of serial No. 22 of that schedule read :
22. Spices, dry fruits and condiments, including 3 per cent. ..., kala namak, ..., but excluding salt. 3. In pursuance of the aforesaid notification the petitioners have been assessed to U. P. sales tax on their sales of kala namak.
4. The petitioners have contended that as kala namak is also a species ot salt, it is exempt from sales tax under Section 4 of the Act, that the aforesaid notification which purports to levy sales tax on kala namak is ultra vires of the Act and that the assessments based upon that notification are also invalid.
5. In their rejoinder-affidavits the petitioners have alleged that the process of manufacture of kala namak consists of heating a mixture of charcoal and sambhar salt. In the counter-affidavits filed on behalf of the Sales Tax Officers, the process of manufacture of kala namak, alleged by the petitioners, has not been admitted. On the other hand, the opinion furnished by Shri S.N. Kapoor, Industrial Chemist, Harcourt Butlar Technological Institute, Kanpur, is appended as annexure to one of the counter-affidavits. That opinion reads:
Black salt is manufactured by heating sambhar or didwana salt in earthen pots, placed inside the furnaces with tanning materials like har bahera, babul bark or any material containing tanning for about 24 hours. The earthen pots or gharas are heated by cinder product obtained from the boilers. After 24 hours the earthen pots are taken out and broken. Black and brownish product is obtained through the process, which is known as black salt. There is no definite ratio between salt and tanning material. The ingredients of black salt are :
(i) Sodium chloride per cent by weight ...98.3 (ii) Total sulphides as sodium sulphides as per cent by weight ...0.44. 6. The question that arises for determination in these petitions is whether or not kala namak can be regarded as salt which is exempt from sales tax under Section 4 of the Act.
7. The learned standing counsel appearing for the respondents raised a preliminary objection that these petitions are not maintainable in view of Clause (3) of new Article 226 of the Constitution (substituted by the Forty second Amendment to the Constitution), since the petitioners have alternative remedy by way of appeal and revision under the Act.
8. As stated earlier, the petitioners have challenged the validity of the aforesaid notification of the Government dated 1st December, 1973. It is well-settled that the appellate and re visional authorities constituted under the Act cannot go into the validity of a notification issued under the Act. Hence, we are unable to accept the contention of the learned standing counsel that the petitioners have any alternative remedy which bars these petitions.
9. Shri Ashok Gupta, learned counsel for the petitioners, contended that the sales tax authorities have not shown that the process of manufacture of kala namak sold by the petitioners was not as alleged by the petitioners. On the other hand, the learned standing counsel contended that disputed questions of fact as to whether kala namak sold by the petitioners was the same commodity as that dealt with in Balwant Singh Jag Roshan Lal's case  26 S.T.C. 129 and was manufactured by the same process as was manufactured by the petitioners in that case, cannot be gone into in these writ petitions.
10. At this stage we may advert to one other submission made by the learned standing counsel. He did not dispute that a subordinate piece of legislation like a notification issued by the Government under the Act cannot overcome the effect of the decision of this court that black salt is exempt from sales tax under Section 4 of the Act. But he maintained that the impugned notification should be read as not being in conflict with the ruling of this court by construing kala namak referred to in that notification as comprising of a species of salt other than that dealt with in that decision. In other words, the aforesaid ruling of this court, according to him, would not come in the way of levying sales tax on any species of black salt other than that dealt with in that case. Elaborating his contention he submitted that the species of black salt dealt with in that decision was produced by mixing ordinary common salt with charcoal and heating it and that hence the aforesaid ruling would not come in the way of levying sales tax on kala namak, which is a different species of black salt which is produced by the process described by Shri S.N. Kapoor. It was contended that since kala namak is a different species of salt manufactured by a different process, there was no impediment to levy sales tax on it (kala namak).
11. For the purpose of these petitions we shall assume that the process of manufacture of kala namak is as alleged by the sales tax authorities and we proceed to examine whether it comes within the ambit of the word "salt" occurring in Section 4 of the Act.
12. The word "salt" has not been defined in the Act. In the absence of such definition, it must be understood according to its ordinary meaning. The following passage "in Encyclopaedia Britannica (1973 Edn.), Vol. 19, page 954, is apposite :
Salt, a mineral substance of great importance to man, is chiefly sodium chloride. It is sometimes called common salt to distinguish it from chemical compounds of the same kind, called salts.
13. In Section 4 of the Act, the word "salt" does not appear to have been used in its widest sense in which it is understood in chemistry, namely, as a chemical compound like acid or alkali, but it is used to connote an Article used for edible purpose. Though sodium chloride is the main species of edible salt, there is no reason to restrict the meaning of that word to sodium chloride alone. There are other species of edible salt besides pure sodium chloride. Even according to the opinion of Shri S.N. Kapoor, kala namak consists of 98.3 per cent sodium chloride and only 0.44 per cent sodium sulphide and other sulphides. There is no dispute that kala namak is used for edible purpose. Merely because it consists of a small percentage of sodium sulphide and other sulphides besides 98.3 per cent of sodium chloride there is no reason why it should not be regarded as "salt". Even if the composition of kala namak sold by the petitioners is different from the composition of the species of black salt dealt with in Balwant Singh Jag Roshan Lal's case  26 S.T.C. 129, the following ratio of that decision is equally applicable to kala namak:
Salt is generally used for eating. The black salt, as we have seen, is also usable for the same purpose, it being useful for digestion....There is no material to suggest that it is not used for digestive purposes. Merely because the black salt may be used for preparing medicine, that would not by itself mean that it is not salt as generally understood. On the scanty material on the record it would appear to us that black salt of the kind manufactured by the assessee was salt as understood in common parlance and hence would be exempt in view of Section 4(1)(a), U.P. Sales Tax Act.
14. However, the learned standing counsel contended that kala namak is not a species of salt, but is a product of salt, since it is produced by a further manufacturing process starting with salt as a raw material. He maintained that the change in the properties of salt brought about by such further process of manufacture, would render kala namak different from "salt" and that it is for that reason that it is known by a different commercial name, namely, kala namak, which clearly indicates that it is different from salt. Support for this contention was sought to be derived from the following observations of the Supreme Court in Sri Siddhi Vinayaka Coconut & Co. v. State of Andhra Pradesh A.I.R. 1974 S.C. 1111 at 1114.
This court has in a number of cases held that the same commodity at different stages could be treated and taxed as commercially different Articles. In A. Hajee Abdul Shukoor & Co. v. State of Madras  8 S.C.R. 217, this court held that 'hides and skins in the untanned condition are undoubtedly different as Articles of merchandise than tanned hides and skins' and pointed out that 'the fact that certain Articles are mentioned under the same heading in a statute or the Constitution does not mean that they all constitute one commodity'. We may also r,efer to the decisions in Jagannath v. Union of India  2 S.C.R. 118, where tobacco in the whole leaf and tobacco in the broken leaf were treated as two different commodities; East India Tobacco Co. v. State of Andhra Pradesh  1 S.C.R. 404, where Virginia tobacco and country tobacco were treated as two different commodities; and Venkataraman v. State of Madras  1 S.C.R. 615, where cane jaggery and palm jaggery were treated as two different commodities.
15. On the other hand, Shri Ashok Gupta invited our attention to the explanation to Section 4(1)(a) of the Act, which states that in that Section "water" does not include mineral water, aerated water, tonic water, distilled water or scented water and that "milk" does not include condensed milk, milk powder or baby milk. He maintained that if the legislature intended that the word "salt" occurring in Section 4(a) should not include kala namak, the legislature would have said so in that explanation and that in the absence of any such mention of kala namak in the explanation, all species of edible salt including kala namak should be understood as coming within the ambit of the word "salt".
16. The passage in the aforesaid decision of the Supreme Court relied on by the learned standing counsel, merely states that after some degree of processing a commodity may become commercially a new commodity and that commodities having different characteristics may be treated different com-modities for purposes of sales tax. But that passage does not lend support to the contention that kala namak does not come within the ambit of the word "salt". We think, Shri Ashok Gupta is right in his submission that if the legislature intended that the ambit of the word "salt" should be restricted to common salt, namely, sodium chloride in its ordinary form and should not extend to other species of edible salt, it is reasonable to expect that the legislature would have said so in the explanation to Section 4.
17. The learned standing counsel next contended that kala namak cannot be regarded as salt as it is used as a spice or as a digestive.
18. We are unable to accept the above contention. Even if kala namak is used as a spice or as a digestive, it does not cease to be a species of edible salt. In Balwant Singh fag Roshan Lal's case  26 S.T.C. 129, this court noticed that black salt was also used for digestion; nevertheless this court held that black salt comes within the ambit of "salt".
19. Thus, it is clear that kala namak, even if it is manufactured by the process alleged by the sales tax authorities, is a species of edible salt and comes within the ambit of the word "salt" occurring in Section 4(1)(a) of the Act. It follows that the impugned notification of the Government, which seeks to exclude kala namak from the exemption granted under Section 4 of the Act, is clearly ultra vires of the Act to that extent.
20. In the result, we allow these petitions and quash the impugned orders of assessment in so far as they levy sales tax on kala namak. The respondents are restrained from recovering from the petitioners sales tax on their sales of kala namak.
21. In the circumstances, we direct the parties to bear their own costs in these petitions.