Judging from the many inquiries that come to the Iowa Agricultural Experiment Station about the composition and merits of "condimental stock foods'' and ''tonics,'' great quantities of these products are purchased by Iowa farmers and feeders. Their sale is built up largely by alluring advertisements, by the use of ''testimonials,'' and by extravagant promises which in some cases cannot possibly be fulfilled. Without question, the consuming public pays out for these various secret proprietary preparations many times what they are actually worth.