Opinion by

Mr. Justice Fell,

This action was to recover the value of land taken by the defendant company under the right of eminent domain for the purpose of building a station. The specifications of error all relate to the admission of testimony offered by the defendant. The main ground of the appellant’s complaint is that the defendant was allowed to prove the circumstances attending the sale of two properties in the immediate vicinity. The plaintiff’s counsel had called the attention of witnesses on both sides to these sales, his own in their examination in chief, and on the cross-examination of the defendant’s witnesses he had shown the prices paid. On the cross-examination of the plaintiff’s witnesses it appeared that one of them had based his opinion of the value of the plaintiff’s property entirely on one of these sales, and that another witness had based his opinion mainly if not exclusively on the two sales. The prices paid for these . properties thus became a standard of value of property in the vicinity. The defendant’s offer was not to show the pric'es paid for these two properties but to prove by the purchasers that the sales were made under special circumstances, and that the prices were greatly in excess of the market values and were not a criterion thereof.

It has been long established that the proper test of the value of land taken under the right of eminent domain is its market value, and that this value is not to be ascertained by proof of particular sales but by the general selling price of land similarly situated. While particular sales may not be proved as estab*487lishing a market value, the good faith of a witness and the accuracy and extent of his knowledge may be tested by questioning him as to particular sales, to ascertain whether he knew of and considered them in forming an opinion. These inquiries go directly to the value of the opinion expressed. We see no reason why a party against whose interest a witness has testified may not show that the opinion expressed is valueless as evidence because it is founded on a misapprehension of the facts, as that a supposed sale has never been made, or that the consideration named was fictitious, or that the sale had been without regard to the market value. This does not lead, as would the proof of particular sales, to the trial of collateral issues. It goes only to impair the value of an opinion which has become evidence in the case by showing that it is based on a misapprehension of the real facts.

The assignments of error are overruled and the judgment is affirmed.