Mr. Presiding Justice Graves
delivered the opinion of the court.
2. Evidence, § 319*—what not admissible to vary terms of written contract. Upon the signing of a contract all previous negotiations and conversations are merged into it, and they are inadmissible to alter or contradict it. 3. Evidence, § 361*—when parol evidence admissible to construe words in building contract. Where a building contract provides that a certain sum shall be paid “when the building is plastered,” expert evidence offered to prove what condition the plastering must be in to fulfill the contract according to the recognized custom in the building trade, held erroneously excluded. 4. Contracts, § 393*—when instruction as to performance of contract erroneous. In an action for breach of a building contract, part of an instruction given for plaintiff stated that if the jury “further believe from the evidence that the plaintiff has complied with her part of the contract, in so far as she could, then your verdict should be for the plaintiff.” Held that the instruction was erroneous in so far as it limited the duty of plaintiff to perform her part of the contract “in so far as she could.” 5. Contracts, § 295*—excuse for nonperformance. One party to a contract cannot enforce it against the other unless he performs it on his part, and it is immaterial whether his failure to perform is due to wilfulness or misfortune. Free access — add to your briefcase to read the full text and ask questions with AI