Determine water contained in soil

For determined the water contained on the soil. Take soil in the container and weight it, after weighted suppose its weight is W1, ie the weight of solid and water (Ws+Ww). Then after that soil is put into oven for 24 hours at 110°C. After it dried again weight, after weighted let weight may be Ws. Then water contained in the soil can be determined by given formula:
         w= Ww/Ws ×100%
Where, Ww = Ws- (Ws+Ww)
It is also to be noted that weight of container suppose to be nearly zero.