. "The whole amount in money to be applied to the purchase ol goodswill be about 90,000, but the Department reserves the right to increase or diminish the quantity of any of the articles named, or substiiuto others in lieu thereof, or to re-quirOt at similar prices, such goods S8 mST bn wanted r,r presents or other purposes, iu the administration of the nf-fairsof the Department." . . .