Gold Bullion as Investment?

The value of money keeps decreasing with each passing year and we need to consider the various types of investments to grow our income. Using the rule of 72, if the inflation rate is 6%, then it takes 72 divided by 6 equals to 12 years for our money to half it actual value. Likewise, if the interests rate is 4%, then it takes 72 divided by 4 equals 18 years for our money to double it present value. Though I cannot afford to buy gold bullion, I will certainly consider investing in government bonds with interests or coupons at 5% currently. There is no minimum to invest and that is the beauty of it. The period is for 3 years and every year I can get 5% more of the principal invested.