Four workers injured in a machinery failure Monday at Johnson Brass & Machine Foundry in Saukville remain hospitalized at Columbia St. Mary's Hospital in Milwaukee, company representatives said Wednesday. The four were burned in the accident when molten brass sprayed out of a centrifuge used in metal casting.Two of the four are in good condition and two are described as being in stable condition but requiring additional surgery, according to a statement from the company. None of the injuries is life-threatening. The company's centrifuges are encased in either concrete or steel and covered with metal lids, the company's statement said. The foundry portion of the business is closed pending an investigation into the cause of the accident. A separate machine shop is operating two full shifts a day.