Does the solubility of iron (iii) oxide increase when the pH of the water it is in decreases? I did an experiment and I got these results:

pH 4: 3.46 
pH 3: 3.77 
pH 2: 2.18 
pH 1: 3.69 
The numbers on the right is the amount of iron oxide remaining that was not filtered.

Do these numbers make sense? (The measurements are in grams.) The original amount of iron oxide in each solution (4 different solutions as there are 4 different pH's) was 3.81 grams

I basically put iron (iii) oxide in different pH's, left them, and filtered out the water after. I measured how much iron (iii) oxide remained. I am not sure if my numbers make sense though because I thought that if the pH drops it increases in solubility. However, my pH 2 was the highest in solubility. Do these numbers make sense chemically?
Iron (III) oxide is insoluble in water. If you add an acid (e.g. $\ce{HCl}$) it might react with the oxide and form a soluble iron salt.

How much of the oxide gets dissolved depends, amongst others, on what acid is used, its concentration and amount, and the time of reaction.