It is a principle well settled, in the law •of agency, that an authority given an agent to sell does not carry with it an authority to sell on credit, but for cash only, unless such be the usage of trade. — 1 Parsons on Cont. 50; Falls v. Gaither, 9 Port. 605. Nor can a special agent, entrusted with the possession of property, who is authorized to sell it, do so by disposing of it in payment of his own debt. A valid exercise of his authority requires that the transaction should be one for the benefit of the principal and not of the agent — a sale proper, and not a mere barter. — Benjamin on Sales, §742; Powell’s Adm’r v. Henry, 27 Ala. 612.
And one dealing with such special agent is'bound at his own peril to ascertain the extent of his authority.— Cummins v. Beaumont, 68 Ala. 204; 1 Brick. Dig. p. 55, § 35.
The first two charges given by the court recognized these-principles, and were authorized by the evidence.
Nor do we see that there was any error in the last charge in regard to the burden of proof. When the plaintiff proved the possession by him of a mortgage on the cotton purchased by the defendants, and that they had constructive notice by the fact of its being recorded, it devolved on the defendants to show that their possession was rightful. This they sought to do by showing a purchase from one Jones, who was alleged to have authority to sell the cotton as the agent of the plaintiff. This authority being only to sell for cash, and its exercise being invoked as a defense, the strict'and lawful pursuance of it must be proved. The onus always rests on each party to prove every material fact necessary to make out his case, or defense. As defendants might be liable for all the cotton traced into their possession, even if Jones had authority to sell, they could only rebut this prima facie case by proving that they paid money or ■cash, the sole consideration for which they could buy. It is *384true that they would be relieved of liability so far as they did pay money, and would only be liable to the extent of Jones’ account which he sought to pay with his principal’s property. Nevertheless the burden of proof rested on them to show these respective amounts, and this was all the charge in question intended to assert. — 1 Wliart. Ev. § 358.
The fact that an attachment was sued out against Jones by the appellee, Hubbard, was relevant, and the writ of attachment was properly admitted in evidence for the sole purpose of proving this fact. It was competent to show a prompt repudiation of Jones’ alleged authority to sell the cotton, and an absence of such acquiescence as might have been construed into a ratification of the act.
The testimony of Allen as to the price of cotton was properly admitted. Taken in connection with the preceding interrogatory and answer, it obviously had reference to the marlteb price of cotton, a conclusion which is largely made up of presumptions, and may always be proved by the opinions of witnesses-based of necessity, in part at least, on hearsay. — 1 Whart. Ev. § 448.
It was also competent to prove the highest price of cotton at any time between the date of conversion and the time of the trial, as it was within the power of the jury, in an action of to'over, to assess the damages of the plaintiff at a sum based on such price, or on a price not less than the value of the cotton at the date of conversion, with lawful interest. — Ewing v. Blount, 20 Ala. 694; Jenkins v. McConico, 26 Ala. 213. This discretion of the jury, in selecting the exact period of valuation, should be exercised in such manner as to prevent the defendant from reaping pecuniary profit through his wrongful act, and, at the same time, in proper cases, to permit the special equities or hardships of the particular case so to operate in the mitigation of damages, as exact justice may require.— Williams, Adm'r, v. Crum, 27 Ala. 468; Loeb Bros. v. Flash Bros., 65 Ala. 526; 6 Wait’s Act. and Def. p. 222, § 9.
We discover no error in the z’eeoz’d, and the judgmezit of the Circuit Court is affizuned.