In Colwill v Reeves [1803-13] All ER Rep 563 Lord Ellenbrough CJ said at 563-564:
If a man puts corn into my bag, in which there is before some corn, the whole is mine; because it is impossible to distinguish what was mine from what was his. But it is impossible that articles of furniture can be blended together so as to create the same difficulty. The goods in question remained distinct, and the messenger might have discovered that they belonged to the plaintiff. He took them at his peril. Whatever fraud there might be in the case, the property was not divested from the plaintiff, and the stratagem is no defence on the general issue to an action at his suit for taking and converting the goods.
Lord Eldon LC said in Lupton v White [1803-13] All ER Rep 356 at pp.358-359:
If a man by his own tortious act makes it impossible for another to ascertain the value of his property, and that in a transaction, in which the former was, not merely under an implied moral obligation, but pledged by a solemn undertaking in a Court of Justice, that such should not be the state of things between them, by those means preventing the guard, which the Court would have effectually interposed, is the argument to be endured, that, as the party, so injured, cannot distinguish his property, therefore he shall have nothing? That is not the law of this country; as administered in Courts either of Law or Equity.
Re Oatway, Hertslet v Oatway  2 Ch 356, passage from the judgment of Joyce J at pp.359-360:
It is a principle settled as far back as the time of the Year Books that, whatever alteration of form any property may undergo, the true owner is entitled to seize it in its new shape if he can prove the identity of the original material: see Blackstone, (2 Bl Com 405) and Lupton v. White ((1808) 15 Ves 432, [1803-13] All ER Rep 356). But this rule is carried no farther than necessity requires, and is applied only to cases where the compound is such as to render it impossible to apportion the respective shares of the parties. Thus, if the quality of the articles that are mixed be uniform, and the original quantities known, as in the case of so many pounds of trust money mixed with so many pounds of the trustee’s own money, the person by whose act the confusion took place is still entitled to claim his proper quantity, but subject to the quantity of the other proprietor being first made good out of the whole mass: 2 Stephen’s Commentaries (13th edn 1899), 20. Trust money may be followed into land or any other property in which it has been invested; and when a trustee has, in making any purchase or investment, applied trust money together with his own, the cestuis que trust are entitled to a charge on the property purchased for the amount of the trust money laid out in the purchase or investment.
Per Staughton J in Indian Oil Corp Ltd v Greenstone Shipping SA (The Ypatianna),  3 All ER 893, at pp. 899, 894 and 906- 907:
Confusio is the Latin word for the mixing of goods belonging to two different owners, so that they cannot be separated. Where they can be separated it is commixtio. The effect in English law was decided as long ago as 1594 in a case described as Anonymous (1594), Poph 38, 79 ER 1156 (or sometimes as Stock v Stock). There the decision of Popham CJ and the Court of King’s Bench was (Anonymous (1594), Poph 38, 79 ER 1156 at 1156-1157):
" the plaintiff pretending title to certain hay which the defendant had standing in certain land, to be more sure to have the action pass for him, took other hay of his own (to wit, the plaintiff) and mixed it with the defendant’s hay, after which the defendant took and carried away both the one and the other that was intermixed, upon which the action was brought, and by all the Court clearly the defendant shall not be guilty for any part of the hay, for by the intermixture (which was his own act) the defendant shall not be prejudiced as the case is, in taking the hay. And now the plaintiff cannot say which part of the hay is his, because the one cannot be known from the other, and therefore the whole shall go to him who hath the property in it with which it is intermixed."
The submission of counsel for the receivers is as follows: where B wrongfully mixes the goods of A with goods of his own, so that the original goods cannot be separated or identified, the whole of the mixture becomes the property of A. So it is a case of 'happy undeserving A', if not also of 'wretched meritorious B'.
Two points of significance in my view emerge from the authorities. First, in some cases a decision had to be made 'not upon the notion, that strict justice was done, but upon this, that it was the only justice that could be done' (see Lupton v White (1808) 15 Ves 432 at 441, [1803-13] All ER Rep 356 at 359 per Lord Eldon LC [where his Lordship was examining decision of the court in Armory v Delamirie (1722) 1 Stra 505 case]). Or as Lord Moulton put it, such cases 'have been little more than instances of cutting the Gordian knot - reasonable adjustments of the rights of the parties in cases where complete justice was impracticable of attainment' (see Sandeman v Tyzack & Branfoot Steamship Ltd  AC 680 at 694, [1911-13] All ER Rep 1013 at 1021). Second, if the wrongdoer has destroyed or impaired the evidence by which the innocent party could show how much he has lost, the wrongdoer must suffer from the resulting uncertainty.
In the days when corn and hay were to be found in heaps which could not be measured accurately, when such disputes were tried by jury and witnesses might be illiterate or ignorant, a rough and ready rule which Goff and Jones describe as punitive may have been the best that the law could find. But a primitive rule is no longer appropriate when modern and sophisticated methods of measurement are available. The measurement of cargoes of oil is, , conducted with care and precision. It will not, of course, achieve absolute accuracy. What method of measurement ever does? But for all practical purposes the quantity of the innocent party’s goods which have gone into the mixture can often be ascertained with a sufficient degree of precision, as it can be in this case. Similarly, there are methods of sampling and analysis which should enable the quality of the innocent party’s goods, and of the mixture, to be assessed
Seeing that none of the authorities is binding on me, although many are certainly persuasive, I consider that I am free to apply the rule which justice requires. This is that where B wrongfully mixes the goods of A with goods of his own, which are substantially of the same nature and quality, and they cannot in practice be separated, the mixture is held in common and A is entitled to receive out of it a quantity equal to that of his goods which went into the mixture, any doubt as to that quantity being resolved in favour of A. He is also entitled to claim damages from B in respect of any loss he may have suffered, in respect of quality or otherwise, by reason of the admixture.