On 1 August 1774, British clergyman Joseph Priestley focused sunlight on mercuric oxide in a glass tube. From this experiment he got a gas that he called "dephlogisticated air". He found that candles burned more brightly in the gas and a mouse lived longer while breathing it. After breathing the gas, Priestley said that it felt like normal air, but his lungs felt lighter and easy afterwards. His findings were published in 1775. It is because his findings were published first that he is often said to have discovered oxygen.