after stating the case, delivered the opinion of the court.

The instructions which were refused asked the court to rule that exclusive use was the correct criterion to determine the classification. The error of this contention seems obvious from the most casual consideration. If exclusive use Were made the test, then an exception would destroy the rule; for however general and universal the use of a particular article might be, if exceptionally used for another purpose, suck use' would destroy the effect of the general and common use, and make the exception the controlling factor. It is urged that if exclusive use is not made the criterion it will be impossible to assess duties, because of the difficulty of ascertaining the chief or general arid common use; but it is manifest that this argument of inconvenience is a mistaken one, and that, on the contrary, it would be impossible to resort to use as a criterion *560 of classification if exclusive use must be ascertained in so doing, for that which is generally and commonly done may be known, but that which is so universally done as to be without any exception is difficult, if not impossible, of ascertainment.

The strength of this reasoning has caused counsel, in the discussion at bar, to admit that the correct standard is not exclusive use, which was presented in the first, fourth, and fifth request to charge, but that suqh test is to be found in the exclusive commercial use which was embraced in the second and third requests. The proposition involves a distinction without a difference. How the line can be drawn between exclusive use and exclusive commercial use, in trade or commerce, is impossible of statement. Indeed, this difficulty is likewise so apparent that in defending the proposition of exclusive commercial use it is defined in the argument to be “ known in commerce,” but known in Commerce is a matter of commercial designation, not of commercial use. Thus it is impossible to state the proposition of exclusive use without being driven by the reason of things to abandon it and seek refuge in the theory of exclusive Commercial use, qr exclusively used in trade or commerce. It is equally impossible to state this last con-, tention without resolving it into a question of commercial designation. The decisions of this court abundantly support the refusal to give the charges asked. Hartranft v. Langfeld, 125 U. S. 128; Robertson v. Edelhoff, 132 U. S. 614; Cadwalader v. Wanamaker, 149 U. S. 532; Walker v. Seeberger, 149 U. S. 541; Hartranft v. Meyer, 149 U. S. 544; Magone v. Heller, 150 U. S. 70 ; Sonn v. Magone, 159 U. S. 417. It is urged that Worthington v. Robbins, 139 U. S. 337, and Magone v. Heller (ub. sup.) áre in conflict with the other cases above quoted, and therefore such other cáses by implication are overruled. The contention is without foundation. , It proceeds upon the hypothesis that this court overruled, in 139 U. S., Hartranft v. Langfeld and Robertson v. Edelhoff, when, in 149 U. S., in Cadwalader v. Wanamaker, Walker v. Seeberger, and in Hartranft v. Meyer, it affirmed those cases, and held itself bound by the doctrine of chief use which was there announced. So, also, it-presupposes that this court, in Magone *561 v. Heller, in 150 U. S., reversed the doctrine established in a line of carefully considered cases without even making reference to them. It is apparent that the matters decided in Worthington v. Robbins and Magone v. Heller do not conflict with the adjudications of this court, as to the chief or predominant úse, which began with the case of Maillard v. Lawrence, 16 How. 251, 261, and has found fuller expression in the line of cases above referred to.

Worthington v. Robbins involved the rate of duty on a certain class of enamel, which it was claimed by the importer was dutiable as watch materials. The court found that the enamel was a raw material, not necessarily material for a watch. a;t all, and not susceptible of being used as such without undergoing a process of manufacture. It was upon this ground the case was decided. Magone v. Heller involved the duty on an article invoiced as “ manure salts ” which the collector claimed was dutiable as sulphate of potash at 20 per cent ad valorem, and which the importer asserted was free of duty as a substance “expressly used for manure.” The proof showed that salts like those in question were used for making fertilizers, that they were sometimes sold to farmers for fertilizing purposes, and that they were also used for making alum, nitrate of potash, and bichromate of potash. In this state of proof the defendant, collector, requested, under the theory of exclusive use, a verdict in his favor, which the court refused, but on the request of the plaintiff instructed a verdict in his behalf. We held that the court rightly refused the instruction for the defendant, which was necessarily an adhesion to the settled doctrine that where use becomes the criterion, exclusive use was not the proper test to apply. We held also that there -was error in instructing for the plaintiff, because the question of whether there was chief or predominant use of the imported article as a substance “ expressly used for manure,” should have been left to the jury, and the case was remanded for that reason. In reviewing the contention we said: “ If the only cojnmon use of a substance is to be made into manure, or to be itself spread upon the land as manure, the fact that occasionally or by way of experiment it is used for a different *562 purpose will not take, it out of the exception. But if it is eommonly, practically, and profitably used for a different purpose, it cannot be considered as used expressly for manure, even if in the majority of instances it is so used.” It follows ■that whilst Magone v. Heller adhered to the settled rule of chief use, a guide was there announced by which to discover whether the- facts established such chief use. Chief use in itself is a vague and uncertain term. Magone v. Heller, therefore, held that chief use was to be ascertained by that which was commonly, practically, and generally done, and was not to be overthrown by an occasional exception for practical or experimental purposes. Thus, we repeat, Magone v. Heller, whilst enforcing and applying the rule of chief use, furnished the instrument for determining and measuring its operation and giving certainty to its application. It is for this reason that in the recent case of Sonn et al. v. Magone, 159 U. S. 417, Magone v. Heller was cited as authority for and in elucidation of the correct test by which use as a measure of classification was to be controlled. The charge given by the court below, and which was excepted to, was manifestly correct, for in giving the rule of chief use the principles by which chief use was to be ascertained were fully stated exactly in accordance with the law subsequently announced by this court in Magone v. Heller.

Affirmed.