in a process for the extraction of celluloses from lignocelluloses , the extraction is carried out by means of heating with aqueous acetic acid under pressure and the addition of formic acid , whereby there is obtained a cellulose with a very low residual lignin content , which can be bleached with ozone and peracetic acid to high grades of white , and acetic and formic acid are recovered by means of distillation , so that waste waters do not , therefore , accumulate .