No contract in writing entered into between a citizen of this Commonwealth and any person, firm, company or corporation, domestic or foreign, doing business in this Commonwealth, for the sale and future delivery of any goods or chattels, machinery or mechanical devices, or personal property of any kind or sort whatsoever, shall be binding upon the purchaser, where the form is printed and furnished by the person, firm, company or corporation, unless all of the provisions of such contract are clearly and plainly printed or written; and, where printed, such provisions and covenants and all stipulations as to the rights of the vendor shall be in type of not less than the size known as ten point; and, wherever in such contract, printed upon a form furnished by the vendor, it is stipulated that the vendor is not to be bound by any verbal agreement or modification of the terms of such printed contract, then such stipulation shall be printed as a separate paragraph or paragraphs and in type not smaller than pica. Should any of the contract, including the special stipulation hereinbefore mentioned, be printed in less than the size of type hereby prescribed, and the agent or salesman of such person, firm, company or corporation enter into any verbal or written or collateral agreement with the vendee, on the part of the person, firm, company or corporation, modifying or changing such printed agreement or the parts of the contract which are printed, then the vendee may, in any action instituted to enforce such contract, or the payment of any sum of money agreed to be paid under such contract, be allowed to introduce such collateral agreement, or contract in modification thereof, or any verbal statement made by the agent or salesman in modification thereof, in evidence in such action, and the same, if proved, shall be considered by the court or jury trying the case as a part of such printed contract.