Claimant, Blanche Peak, filed her claim as widow and dependent of Robert Henry Peak, a former employee of Winding Gulf Collieries Company, before the State Com*454pensation Commissioner, on January 28, 1953. On February 18, 1955, the commissioner denied the widow’s claim, “on the ground that claimant did not die from silicosis in its third stage accompanied by tuberculosis”. Upon appeal, the Workmen’s Compensation Appeal Board, on August 22, 1955, affirmed the order of the commissioner.
The employee ceased work on February 24, 1947, and from that date to the time of his death was continuously and totally disabled. On October 30, 1947, he filed his claim with the State Compensation Commissioner and, after full hearings, was found to be suffering from the disease of silicosis, second stage, and was awarded and paid $1,600.00.
On January 10, 1953, about three-thirty o’clock in the afternoon, on directions of his personal physician, the employee was admitted to a hospital for treatment of the silicotic condition, with instructions by the physician to place him in an oxygen tent, if his condition later indicated the necessity therefor. At eight o’clock P. M. of the same day his pulse was 54 and his respiration 18. At twelve-thirty A. M. of the following day his pulse had increased to 116, and his respiration to 36. The physician was asked: “From the pulse and the respiration between those two times would you consider that his condition was getting grave or serious?” His answer was: “I think so, yes”. At two-thirty A. M. of the same day his pulse had increased to 120 and his respiration to 40. He was at that time placed in an oxygen tent. At about four o’clock A. M. of the same morning the oxygen tent caught fire and the employee, husband of claimant, was severly burned about the chest and face. He died at five-fifty A. M. the same day, January 11, 1953. From the evidence before us there appears no question that the fire was caused by the striking of a match by Robert Henry Peak, for the purpose of lighting a cigarette. Neither does there appear any doubt that he had been warned by employees of the hospital *455as to the dangers of attempting to smoke while in an oxygen tent. The patient was not placed in an oxygen tent after the fire for the reason that no other tent was available.
Six days after the death of Peak, an autopsy was performed on his body by a competent pathologist. The autopsy disclosed that Peak, at the time of his death, was suffering from an “unusually advanced stage of pneumoconiosis or silicosis, third stage”. The pathologist further testified: “I would say it was one of the most severe cases or most wide spread silicosis I have ever seen in my own material and in the material of others”. No evidence, however, was found by the pathologist that Peak had active tuberculosis at the time of his death. There is evidence that he suffered from tuberculosis subsequent to the time of his last exposure but that it had been arrested prior to the time of his death. The report of the Silicosis Medical Board, dated September 17, 1954, stated: “After a careful review of the record in this case, including the death certificate and an autopsy report, dated January 17, 1953, and signed by Dr. W. A. Laqueur, Pathologist, it is the opinion of the Silicosis Medical Board that this claimant at the time of his death did suffer from the disease silicosis in its third stage. Since this is a claim under the old law and the statutory requirement was that the claimant at the time of his death must be suffering from the disease tuberculosis in active stage, the claimant must be denied an award under this condition due to the statutory requirement that active tuberculosis be present which was not demonstrated by autopsy.”
It is contended that the death of the employee resulted from the oxygen tent fire and that such oxygen tent fire constituted an intervening cause, breaking the causal connection between the industrial injury and the death of the employee. We are of the opinion, however, that the record does not necessitate a finding that death of the employee was caused by the burns resulting from the tent *456fire. It is clear, from the report of the Silicosis Medical Board, from the findings of the commissioner and of the appeal board, as disclosed by its order and opinion, referred to in the order, that the death of the employee was considered to have resulted from silicosis in the third stage. We think such finding amply supported. The pathologist gave no evidence concerning any internal burns or death by inhalation of fumes, and no other witness testified to any such effect. It is true that the personal physician of the employee gave as the cause of death on the death certificate, “Pulmonary edema due to burns and inhalation of fumes from fire in oxygen tent. Myocardial insufficiency”. The physician stated, however, that he did not see or examine the employee after the fire and did not know whether there were internal burns. It is not contended that the external burns suffered by the employee caused his death. On the other hand, we think the evidence ample to support the finding that death of the employee resulted from silicosis in the third stage. As before noticed, the pathologist found “an unusually advanced stage” of silicosis in the third stage, and that “it was one of the most severe cases or most wide spread silicosis” he had ever seen. It is not disputed that the employee was totally and continuously disabled by silicosis for several years prior to his death, and his personal physician, who had treated him during those years, testified to the effect that the employee “had been steadily deteriorating during that time”; that when he caused him to be admitted to the hospital the last time he considered him “gravely ill”; and that he “was expecting” the death of the employee and had advised the. employee’s family “that he was gravely ill”. When we add to such facts the very rapid increase in the pulse and respiration rates of the employee before he was placed in the oxygen tent, we think a sufficient basis for determination of death because of the disease silicosis is demonstrated. At least, we are not able to say that the findings of the commissioner, the appeal board, and the members of the Silicosis Medical Board, physicians and surgeons, were plainly wrong.
*457It will be noticed that the date of the death of the employee, January 11, 1958, was subsequent to the effective date of Chapter 136 of the 1949 Acts of the Legislature, July 1, 1949, while the date of the last exposure of the employee was. prior to the effective date of that act. Prior to such effective date the statute required that silicosis must be accompanied by active tuberculosis to constitute silicosis in the third stage. By the 1949 Amendment the definition of silicosis in the third stage was changed to read: “* * * when it is found by the commissioner that the employee has silicosis resulting in total permanent disability, whether or not accompanied by tuberculosis of the lungs”. Since, in the instant case, the cause of the death of the employee was silicosis in the third stage, unaccompanied by active tuberculosis, the question naturally arises whether the widow-claimant should be permitted to recover in accordance with the amendment, or whether her right of recovery should be denied because of the provisions of the former statute in effect at the time of the last exposure of the employee, requiring the existence of active tuberculosis to constitute silicosis in the third stage. In the instant case, counsel for the respective parties agree that the statute in effect at the time of the death of the employee should govern as to the rights of the dependent widow, but it seems necessary to further consider the question here.
We think the basis for the answer to the problem was pointed out in Gibson v. State Compensation Commissioner, 127 W. Va. 97, 31 S. E. 2d 555, wherein it was held: “1. A claim for death benefits, provided for by Code, 23-4-10, is separate and distinct from an injured employee’s claim for disability benefits.” In so far. as we are able to determine, that holding has never been seriously questioned. The problem now before the Court was considered in the case of Webb v. State Compensation Commissioner, 138 W. Va. 21, 76 S. E. 2d 248. In that case death of the employee occurred after the effective date of the amendment. The dependent widow claimant was held entitled to an award under the provisions of the *458amendment, notwithstanding the last exposure of the employee occurred before the effective date of the amendment. In that case, however, there had been a finding and an award to the employee for silicosis in the third stage. In a later case, No. 10649, styled Agnes Louise Webb v. State Compensation Commissioner and New River Company, decided February 9, 1954, without an opinion, this Court adhered to the holding in the first mentioned Webb case, stating in the order entered therein that the issue in that case was “controlled by the principles laid down in Webb v. State Compensation Commissioner, decided by this Court February 10, 1953, 76 S. E. 2d 248”. These cases, we think, constitute clear authority for the proposition that the rights of such a claimant are to be governed by the statute in effect at the time of the death of the employee.
In Hirsch v. Hirsch Bros., Inc., 97 N. H. 480, 92 A. 2d 402, the Court held: “4. Workmen’s Compensation Law existing when employee died, and not when accident occurred, determined compensation rights of employee’s dependents * * See Larson’s Workmen’s Compensation Law, Section 64. 10.
We find no substantial reason to question the holding in the Gibson case or in the Webb cases. It is clear that no right accrues under the statute to a dependent of an employee until the death of the employee. In fact, no right may ever accrue, for the employee may not die within the six year period following his last exposure. This being true, it is clear, we think, that the application of the statute in effect at the time of the death of the employee, the time of the accruing of the rights of the dependent, should govern as to such rights. In so applying the statute, no vested right is disturbed, for the simple reason that none existed, or could exist, before the death of the employee. An act of the Legislature, though it have retrospective effect, is not necessarily invalid, and does not, for that reason, come into conflict with any constitutional provision, unless vested, not potential, rights, *459are disturbed. See Huntington Water Corp. v. City of Huntington, 115 W. Va. 531, 177 S. E. 290; City of Benwood v. Public Service Commission, 75 W. Va. 127, 83 S. E. 295. It is true that this Court has held, we believe correctly, that the basis of liability of employers under the Workmen’s Compensation statutes, is contractual. But we can not say that such contractual relationship or liability necessarily precludes a subsequent Legislature from effecting changes in the Workmen’s Compensation laws. Those who enter into such contractual relationships do so with knowledge of the right and power of the Legislature to enact any new law relating to the subject matter, not in conflict with any constitutional provision, and must be presumed to have agreed t'6 any such change.
The further contention is made that since the holding in the Webb cases precludes the relitigation by the employer of the question of the existence of silicosis in the third stage where there had been a prior determination of silicosis in the third stage, the 1949 Act should be interpreted and applied so as to preclude the relitigation of such a question in every case where any determination of such a question had been previously made, whether such a determination resulted in a finding of silicosis in the third stage, in the second stage or in the first stage. But the pertinent act, Chapter 136, Article 4, Section 6-a, applies only where “the commissioner has determined at the time of the original award that he was suffering from silicosis in the third stage”. To hold that the act applies to “determined” first or second stage silicosis would amount, in effect, to an insertion of language in the act of implication, which is neither required nor warranted. Where the prior “determined” stage of silicosis is third stage, the employer is necessarily a party to the proceeding wherein the determination is made, and the employer has been afforded opportunity to litigate the question and to contest such determination. The employer alone is precluded by the statute since he, and not the potential dependent, is a party thereto. To say *460that the language of the 1949 Act applies to every prior “determined” stage would deny to certain dependents the right to litigate their claims because of findings in a proceeding wherein they were not, and could not have been, parties to the proceeding. ' Such a result can not be justified from the language of the statute, and should not be read into the statute by implication.
It necessarily follows that the order of the Workmen’s Compensation Appeal Board appealed from must be reversed; that the order of the State Compensation Commissioner, denying an award to claimant, must be set aside; and the case remanded to the State Compensation Commissioner for the entry of an order in accordance with this opinion.
Reversed and remanded with directions.