The special reserve fund shall be invested according to existing laws relating to investments of capital by fire insurance companies, and shall be deposited as the fund shall accumulate and be invested, with the insurance commissioner of the state, who shall permit the company depositing the fund to change deposits by substituting for those withdrawn others of equal amount and value, and to collect and receive the interest or dividends upon those securities as the interest or dividends may accrue. The fund shall not be regarded as any part of the assets in possession of the company, so as to be or render the company liable for any claim for loss by fire or except as provided in this chapter.