(_d_) For the purposes of this paragraph any coal-tar product provided for in this act shall be considered similar to or competitive with any imported coal-tar product which accomplishes results substantially equal to those accomplished by the domestic product when used in substantially the same manner. [20] Upon American selling price or United States value. [21] The relevant provisions of this act are as follows: Par. 27 (b) ... phenol, carbolic acid which on being subjected to distillation yields in the portion distilling below one hundred and ninety degrees centigrade a quantity of tar acids equal to or more than 5 per centum of the original distillate, ..., and any mixture of any of the foregoing products with any of the products provided for in paragraph 1651, 20 per centum ad valorem and 3½ cents per pound. (c) The ad valorem rates provided in this paragraph shall be based upon the American selling price (as defined in subdivision (g) of section 402, title IV), of any similar competitive article manufactured or produced in the United States. If there is no similar competitive article manufactured or produced in the United States then the ad valorem rate shall be based upon the United States value, as defined in subdivision (e) of section 402, title IV. (d) For the purposes of this paragraph any coal-tar product provided for in this Act shall be considered similar to or competitive with any imported coal-tar product which accomplishes results substantially equal to those accomplished by the domestic product when used in substantially the same manner. [22] In 1923 the unit value of domestic sales was 27 cents per pound and the duty on imports (computed specific rate per pound) was 16 cents; in 1925 the corresponding figures were 21 and 16 cents, respectively. [23] Par. 1651. Coal-tar products: ..., all mixtures of any of these distillates and any of the foregoing pitches, and all other materials or products found naturally in coal tar, whether produced or obtained from coal tar or other source, and not specially provided for in pars. 27 or 28.... [24] Par. 27 (a) (2). Coal-tar products: All distillates (except those provided for in sub-paragraph (b)) of coal tar, blast-furnace tar, oil-gas tar, and water-gas tar, ..., which on being subjected to distillation yield in the portion distilling below two hundred and fifteen degrees centigrade a quantity of tar acids equal to or more than 75 per centum of the original distillate. [25] Par. 27 (b). Metacresol having a purity of 90 per centum or more, orthocresol having a purity of 90 per centum or more, paracresol having a purity of 90 per centum or more, ... and any mixture of any of the foregoing products with any of the products provided for in paragraph 1651, ...