An apparatus and method for automatically producing a desired specific gravity of a salt solution used for deicing highways. Highway departments can produce a high volume of salt solution of a desired specific gravity by a machine that automatically feeds salt and water into a hopper tank to produce brine, then automatically measures and adjusts the specific gravity of the brine by adding greater or lesser amounts of fresh water to the brine removed from the hopper tank. The salt added to the hopper tank contains impurities, which are removed by self-cleaning strainers. The sediment so removed flows to a trash tank. Sediment in the trash tank settles to the bottom thereof and the liquid collected is filtered by another set of self-cleaning strainers such that liquid from the trash tank can be sent to the hopper tank. The device automatically records the specific gravity of the solution produced.