C.S.P. Singh, J.
1. The additional revising authority has referred the following two questions for the opinion of this Court:
(1) Whether 'pumping sets' are liable to tax as machinery in view of the retrospective amendment of item No. 52 of the First Schedule to the U. P. Sale Tax Act by the U. P. Sales Tax (Amendment) Act of 1974 ?
(2) Whether stone 'chakki ka patthar' and 'rubber beltings' are covered by the term 'mill stores and hardwares' and are taxable as such under the years in question ?
2. So far as the first question is concerned, in S. T. R. No. 478 of 1977 (decided by me today) (Sterling Machine Tools v. Commissioner of Sales Tax, U. P.  43 S.T.C. 72), it has been held that 'pumping sets' are liable to tax 'as machinery parts'. The question is disposed of accordingly.
3. The second question relates to the taxability of stone 'chakki ka patthar' and 'rubber beltings'. The category of items comprised within the term 'mill stores and hardwares' were considered on a number of occasions by this Court. Reference to the Full Bench decision of this Court in Commissioner of Sales Tax, U. P. v. Ram Niwas Puskar Dutt  28 S.T.C. 736 (F.B.) is sufficient for elucidating the principles on which the question is to be resolved. The Full Bench approved of the test laid down in the two earlier decisions of this Court for determining as to whether an article fell within the category of 'mill stores and hardwares'. The two cases were Commissioner of Sales Tax, U. P. v. Aftab Husain Imdad Husain  25 S.T.C. 471 and Fine Trading Corporation v. Commissioner of Sales Tax, U.P.  25 S.T.C. 474 In Aftab Husairis case  25 S.T.C. 471, it was held that 'hardwares and mill stores' were allied trades, and that 'mill stores' consisted of items like small tools and spare parts of machine, and that 'hardware' by itself ordinarily refers to items of base metal like nuts, bolts, hinges, etc. In Fine Trading Corporation case  25 S.T.C. 474, it was held that 'mill stores and hardwares' had been deliberately set down as comprising between themselves a single category and the word 'hardware' in the entry took its colour from 'mill stores'. Expanding this test further, the Full Bench held that the expression 'mill stores and hardwares' comprised of articles which had something common with each other. Once the test in Aftab Husain Imdad Husain's case  25 S.T.C. 471 is applied, viz., that 'mill stores' comprises items like small tools and spare parts of machinery, rubber belting would not come within the category of 'mill stores'. They are obviously not tools and also not spare parts of machinery.
4. In the case of Vithal Chhagan & Sons v. State of Gujarat  17 S.T.C. 96, the Bombay High Court held that a spare part is a part which is severable and capable of being substituted or replaced by another, or otherwise there would be no point in having an additional or extra part or carrying, holding, or keeping such parts in reserve for future use, or to supply an emergency. This Court has also considered the matter in Bajoria Halwasiya Service Station v. State of U. P.  26 S.T.C. 108 It was held that in the popular sense, spare part when used with reference to motor vehicle is the duplicate part of motor vehicle kept in readiness to replace a loss or breakage, etc. Rubber belting would meet none of the tests laid down in any of these cases as they are not component parts of the machine on which they are used. The position appears to be different so far as 'chakki ka patthar' (stone) is concerned. The taxing authorities have found that these stones are used either for preparing flour or surkhi. They are fitted to the machine which grinds the material required for preparing flour or surkhi. They are thus, obviously, 'spare parts' of the grinding machine.
5. Before parting with the case, it is necessary to point out that not all spare parts of machinery would come within the category of 'mill stores', but only such spare parts of machinery as are related to mill stores trade. This is so because if every spare part of machinery is put in the category of 'mill stores', there will be nothing left for the entry relating to spare parts of machinery to operate upon.
6. The first question is, therefore, answered in the affirmative ; the second question by saying that stone 'chakki ka patthar' is covered by the term 'mill stores', but not rubber belting.
7. In view of the partial success and failure of the parties, they shall bear their own costs.